So recently i picked up a 1996 Gmc Jimmy 4x4 with a 5speed manual. 138000 miles. It has been good but seemed like it had a little bit of a miss from the get go. Usually I am a fairly slow driver but today i was in a bit of a hurry. 60-75mph for about 30 miles or so. On my way back home I had it in cruise control and it shuttered bad. A real hard miss. I downshifted to fourth and it still missed in the lower rpms but after 2k it seemed fine. I get to a stop sign and put it in neutral and on its own, the jimmy revs out to 2k rpm on its own. It drops to about 1500 then climbs to about 3k then back down to regular idle. I take off to put it on the scanner and when i get about 55 i notice it is accelerating on its own. I'm not a big fan of vehicles going faster than I want. So I put it on the scanner and it says i need a Engine Coolant Temp Sensor. It also says transmission control system malfunction, and I didn't think a manual shift should throw that code? Well i'm still driving it but it still misses and revs intermittently. I really need input as this is my daily driver. Thanks!

 

Clean the egr vakve and also clean the iac valve

This shows you how to clean it

the iac can be cleaned with the same stuff

https://blazerforum.com/forum/articl...-thread-18901/

Its worth a try it prob wont fix the problem but its a start

 

Does your scanner provide a live data stream? My 97 did the same thing. When it acted up i was showing a bunch of sensors going blank. All those sensors shared a refence voltage. One sensor was shorting out intermittedly. When it shorted my truck went insane. BTW only one code popped up. Showed as a TPS sensor circuit voltage low.

Let us know!

 

ok i'll clean the egr and iac this weekend. The scanner has no live data stream. It says engine coolant temp circuit high output. I messed up my engine coolant temp sensor replacing my alternator but when replaced that code goes away. It also gives the transmission system malfunction. And 1 or 2 other codes now but the scanner for some reason can't provide data for? Thanks!

 

The only way I caught my problem was the data stream.

 

I noticed today that both problems clear up if i mat the throttle. Goes many miles with no revving or missing