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My 96 RM again. A few long highway trips, and another 25+ mpg rating (I hasten to add, Imperial gallons!) It idles like new and is smooth in the pull - but at low throttle it 'lopes" - and I've had it stumble and threaten to stall pulling away.

I'm thinking throttle position sensor. Does anybody have a review on which are the best TPS's, or a preference as to whether to go genuine GM or the aftermarket? I called the local GM dealer today, GM still stocks TPS's for it but the nearest one is two weeks away and $104 + tax.
 

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If the dealer is selling you an AC delco you could have one on your doorstep from Rockauto monday the 18th for 54 cdn bucks.

Now is it the TPS ? Maybe, maybe not .
Have scanned or read actual voltage ?
Should be a,smooth rise with no drop outs or glitches.
Could be so many different things
 

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I'm thinking throttle position sensor.
Since you're thinking throttle position sensor, to avoid being redundant:

IAC motor?
Clean MAF sensor?
PCV Valve?
EGR Valve?

Firing the parts cannon is usually not a good idea, but the parts derringer is cheaper.
 
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Reactions: Caddyshack95

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Treat yourself to the enhanced quality of life available by searching the numerous stickies and other general threads re: 'off-idle stumble'. As offered above, you can spend booquoo bucks on new parts that end up just being periodic maint. replacements that your car absolutely loves you for. But it'll still be sad that you missed a loony's worth of spongy or holey vacuum hose that actually fixes the problem.
 
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Reactions: Brick B-Body

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Get a scanner and diagnose it. It's so easy to go down the rabbit hole of throwing parts. I'd say vacuum leak but it could be anything and without proper testing steps it is a guessing game
 

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There are so many issues that a scan can not find, but is a good idea to do the scan first. Do the easy stuff first, such as checking the vacuum hoses (bet you will find at least one bad even if not the problem you have. Spark plug wires (pop the hood in the dark and look close for signs of light from wires sparking to ground or cross firing each other). Dirty MAP OR MAF sensors and throttle body. Change the spark plugs (if already done, does not mean one or more are not defective), If the oxygen sensors will break loose, clean them and reinstall with anti-seize ON THE THREAD ONLY. Change that fuel filter anyway, and use a good fuel treatment additive. You need to be using an ethanol treatment at each fuel fill-up on all cars and trucks before 2007 because of corrosion (Stabil Marine 360 is a good one). If all that fails, get a scan test run that has the capability to test, not just scan, all ECU functions before replacing parts. I have known people that replaced a bunch of parts, some that fixed a problem, but didn't know which one fixed it, so at least replace one at a time. One last thing, sometimes the ECU needs a little time to learn a new part. Hope any of this helps you or any others.
 
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