Stumbling at more than have throttle

[ice111103]

I have been dealing with this stumbling/miss problem for about 6 months now. The car mostly sits but about once a month I try and get out there and figure it out. The car starts fine but while cruising if you press on the gas at more than half throttle is will start to stumble. If you keep the pedal down it will continue as the RPMS SLOWLY rise. If you let off the pedal slightly and then reapply more gradually it sometimes fixes the problem and will accelerate normally. The car does this every time you attempt to accelerate now. It use to only to do it between 2-3K in the first month.

I was getting

83 - High Electro Drive Fan circuit fault - A/C and Fan Circuits
EGR Control solenoid - Solenoids
3.0L SHO - Low Speed Fuel Pump Relay circuit - Power / Fuel Pump Circuits


The only codes that I am getting now is

91 (running lean)

What I have changed with no effect:

Fuel filter
Ignition coil
TPS
CCRM
Unplugged capacitor on ignition coil

Fuel pressure is 22-24 PSI KOEO. Car running at idle was 30-32 PSI and with vacuum line pulled 40 PSI and fuel pump does not whine.

The CEL stopped working a little before it started to do this. The bulb is good so there is a wiring issue. I don't know if this is connected or not.

I am getting really frustrated with this thing since it has been so long. Any help would be greatly appreciated.

Thanks,
Anthony

 

[The Guru]

FWIW, I had the exact same problem when I swapped engines.
I pulled the upper intake to discover that the the vacuum lines under it that go to the actuators that open the secondaries where cut or rotten.

 

[NotSoSlowSHO]

I see that you have already replaced the TPS.

The TPS would be my suspect #1

Suspect #2 would be the MAF.
Try unplugging the MAF, see how that effects things.

 

[ice111103]

I see that you have already replaced the TPS.

The TPS would be my suspect #1

Suspect #2 would be the MAF.
Try unplugging the MAF, see how that effects things.

I changed the TPS with no effect.

I am running a 80 Mark VIII MAF with an LPM. Think I should swap back to the stock MAF and remove the LPM?

 

[ice111103]

FWIW, I had the exact same problem when I swapped engines.
I pulled the upper intake to discover that the the vacuum lines under it that go to the actuators that open the secondaries where cut or rotten.

I replaced those those when i did the swap (2000 miles ago). I had to get some longer lengths because when I put the intake back together (had it ported) I mixed up the BBBs and the ******* were facing the wrong way. I just used longer vacuum lines instead of taking it all back apart.