Couple questions

[Dave M]

Hello, I have a few concerns about my 98 SHO with 81,000 miles.
My first worry happens when i'm stopped at a light. With the a/c off and my foot on the brake the tach revs from 600 to a 1100 rpm over and over. Today I allowed the car in front of me to start off and instead of giving it gas I just took my foot off the break when this odd revving was happening. the car actually surged forward---not the usual idling forward--and immediately following this episode, the next few times I pressed the pedal, the power transfer felt sloppy and the transmission refused to downshift when it normally would. Prior to all this hoopla, when I turned the engine over it revved into the 3000 range which is very high for starting the car right? the noise was shocking. Is this transmission related? any guesses?

Secondly, I'm getting a distinct popping noise from the rear of my car when going over hard bumps. backseat passengers say they can "feel it" popping near their feet when it happens. any guesses?
And lastly, (sorry for the list) when replacing struts and when money is tight, is it o.k. to just do two at a time? If so, which will benefit more from new struts, the back or the front? Even with the car off, I get bounce (and not just a little), floating at high speed and many other symptoms that lead to believe it's time for a change. anywho, thanks for the advice
bests, dave m

 

[SHOZ123]

The idle is either the TPS or the IAC valve. The TPS isn't very expensive and easy to change, the IAC can be taken off and sprayed with some carb cleaner. Also clean the MAF sensor with some residue free contact cleaner.

If the popping is felt by your passengers in their feet it is either the tension strut bushings or the sway bar bushings. My guess is the sway bar bushings.

Yes you can change the struts in pairs. The SARC struts will wear and show weakness around 80k. Pull the SARC fuse and see if you like this (disregard the lack of PS for now). If you do you can just unplug the struts or the strut sensors and they will be in hard mode 100% of the time.

 

[Majisto]

The first symptom really does sound more like MAF then IAC. When my IAC got clogged, the car would start up, then choke and stall. IAC usually acts up when you turn on the AC since when it's clogged it can't compensate for extra load.

Thankfully, both are quite easy fixes, and last I checked, MAFs weren't that expensive. I know IACs run about $50-70 depending on where you buy them from, but cleaning with Carb. Cleaner has always been fine for me.

 

[Dave M]

Thanks for the suggestions.
In regards to the idle issue, i recently cleaned the intake and sprayed contact cleaner on all of the sensors, including the MAF sensor. hmmmm...could they gunk up that badly so soon?
this was less than 1000 miles ago...
And in regard to the clunk in the back, I installed a 26mm rsb and new poly endlinks and bushings just 10,000 miles ago. I often hear what others have described as those poly fittings working because of their trademark noise. I had sway bar links/bushings in the front before and the noises/sqeaks/et cet were much different than the noise i'm getting now over hard bumps in the rear. it's more like something is popping very quickly in and out of a rubber housing, but i guess that describes the bushings too, huh?

sure wish sarc struts were cheaper too
Thanks again guys, dave m