Ongoing running issues/hesitation on a 96

[sickSHO96]

This is gonna be a bit of a story so bear with me... It's been an ongoing problem for about a year or so now and with gas being so expensive I need to get this nipped in the bud once and for all.

1996 SHO, true mileage unknown (car was from Canada with gauges reading Km/h swapped out for a US-spec cluster, never saw the original) but thought to be around 80k. Everything was fine until my transmission went out. I was going to tackle the swap myself until I quickly found out that I couldn't get the car high enough in the air to drop the subframe and everything have clearance under the car so I took it to a shop. When I got it back, I realized that it ran like shit, so I put some fuel treatment in with a fill up. That didn't work, when I got it home I saw that the breather tube was NOT secure to the TB and the battery tray was unbolted. Fixing the obvious didn't fix the problem, so I shipped off my X3 to get the screen fixed, going to Advance Auto in the meantime. They told me bank 1 O2 sensor was bad so I replaced it, forgetting at the time bank 1 is in the back and I did the front (recently replaced the back though). Still didn't run right, and to put a damper on progress the wire from the PCM to the ignition switch snapped, introducing a no start problem that I couldn't track down for awhile. During the SHO's downtime, I got my X3 back and when I got the car running again I pulled the following codes:

P0133
P1130
P1132
P0172
P0231
P1469
P1000

At this point I returned the PCM to stock for proper diagnosis, but it was undriveable without a tune to activate at hard throttle and being my daily driver and not having time to really tear into it and track down these problems, I had to reload the tune and drive it like that. This really defined the problem though. Under throttle the car will bog, I'd have to tap the pedal to the floor briefly to get the PCM to register WOT and run open loop, seemingly during which I would have no problems. Anything under about 3/4 throttle gave almost no power. Also above 3000 RPM I seemed to have no problems. At idle the car shakes very bad, though it seems to randomly cycle between running rough and running PERFECTLY. Wiring open the secondaries seemed to exacerbate the problem, so I returned the butterflies to their stock configuration.

In the process of messing with the X3 I disconnected the battery resetting the PCM. Reading the codes again showed that p0231 was gone but the others remained.

Also around this time I did some work on a friend's SHO and driving it noticed that my SHO was very underpowered at WOT. During a recent drive on the interstate however, while I was trying to catch up to traffic redlining second gear (don't ask why), I physically FELT what I would guess was catalyst material dislodging itself from my exhaust. There was a thump, then my car rocketed forward and apparently I had all my WOT power back. When I got home and put the car in park, it was idling at 2k, but killing it and restarting brought it back down to normal and it hasn't idled high since.

A couple days ago I finally got around to replacing the bank 1 upstream O2 and cleared the codes. I'm still getting P1130, P1132, P0172, P1469, & P1000, but I don't have to push the throttle so far to get my power now. It also seems to run a little more evenly now. Basically at this point I'm trying to figure out what I should look at next. I've installed and tested as many known working sensors as I could think of, except for the CKP, CMP, DPFE and maybe a couple others. Also, since the car is my daily driver I was waiting to pull the surge tank until I exhausted all other options. Is now the time to check the rear plugs/coils? I figured they shouldn't be too bad since it hasn't been too long since I changed everything back there.

Thanks in advance for any help.

 

[SHOZ123]

Are you sure the O2s are plugged into the proper plugs? IIRC the post cat O2s use the blue plug and the pre cat ones use the green plug

You could very well have had a plugged cat.

P1000 is nothing.

P0172, P1130 and P1132 all point to bank one sensor one being at it's adaptive limit or not switching. There is either a horrendous vacuum leak on that bank, exhaust leak on that bank or the senor is bad.

P1469 is the AC cycling too often or too short of cycle.

 

[sickSHO96]

That's the way it looks from the sensors on the old y-pipe from my last SHO, but there appear to be tabs on the sides of the plugs that slide into grooves in the wiring harness connector preventing the upstreams from being plugged into the downstream connectors. I'll give it a double-check regardless because there's no telling what if anything the tranny shop fudged while they had it. I also plan on smoking out the intake to check for leaks. I'd like to take a proper reading with the car running but the needle on my vacuum gauge is offset from 0. It still reads pressure changes, but it doesn't accurately read the right pressure. Would it be 'safe' to take it apart and try to reset the needle manually?

 

[sickSHO96]

Just got done smoking out the intake... Couldn't see any leaks but in the process I broke a little plastic vacuum line. Started the car and flicked the throttle a little and listened to the vacuum leak to see if it was really bad (I'm gonna seal it anyways) but in the process I'm pretty sure I heard something shorting out around the rear coils, or maybe I'm tripping. Could be unrelated or nothing but I'm gonna pull the surge tank and check things out anyways...

 

[sickSHO96]

Well, after a day's worth of searching, I got 3 new coils and 4 new plugs. 2 in the rear appeared to be original so they had to go, plus one of them was broken at the connector and all 3 in question were cracked. I do remember replacing a coil when I welded the cams, but I thought I replaced all of them... I ended up keeping the replacement coil installed. Upon inspection of the old plugs (again, not really all that old), #3 was gapped to like .02 something, thinking it could have been causing some problems potentially. Before I put it all back together I reinsulated the wiring harness back there. The first start was promising, the test run was pretty good, but I still feel a miss at idle so I'm thinking this was unrelated, yet still something that needed attention. I'll post new DTCs after work or whenever the PCM sets them.

Stuck the camera under the car and took some pictures of the sensors and I'm a little confused... It looked like they all had blue connectors, but I won't be able to actually jack it up and take a good look until I can get a new jack. The plug on the sensor I pulled was blue as well.