Truck runs rough most of the time at idle and when cold, can lunge ahead when rolling to a stop. Sometimes notice a fluctuation in RPMs when climbing hill (3000 rpms). Seems to be worse when cold.
This make/model has a chronic problem with EGR clogging. If you have a dashboard indicator showing "check engine" most likely it is a trouble code indicating and EGR (exhaust gas recirculator) valve problem. Symptoms are rough idle, and surging and stalls.
What happens is sediments from the exaust manifold get sucked up into the valve when it opens, then stick in the valve and keep it from closing. When the valve is open when it should be closed, the engine runs very rough.
I removed my egr and then dislodged the sediment (pea-sized debris) and then re-installed the valve. Three days later, the same "check engine" and same rough idle. I must have did this at least three or four more times.
What I found that gave me a permanent solution was an aftermarket filter gasket that keeps debris from clogging. I don't remember the name of the product, but a search for "EGR filter gasket" may lead you to the product.
Install the gasket between the EGR and the exhaust manifold and you should be good to go. Note: on 1995 and newer models, disconnecting the EGR from the wiring harness (common on R&R) may require the computer to be reprogramed.
The EGR was the problem for me as described by mycraisemai. Thanks for your post! You saved me lots of time and money.
Check for fuel press regulator leak, and/or vacuum leaks.
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rough idle sometimes even stalls poor acceleration low rpm @ idle
My 95 s10 pickup with 4.3 runs fine but idles rough at stops like it's going to stall. The "service engine soon" light has just recently gone on and might be related. The only thing I've done so far is put some fuel injector cleaner in the gas tank yesterday. I'd appreciate any help. Thank you.
Chev S10 4.3L V6 rough idle and under power"
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