Rough idle

Asked by Mar 27, 2016 at 10:35 PM about the 1991 GMC Sierra 1500 C1500 SLE Extended Cab LB

Question type: Maintenance & Repair

Rough idle won't stay running have change
elec.spark control, idle air control,plugs,map
sensor,tps, and the ecm.. Still running rough but if
you unscrew the IAC it idles high but the miss
smooths out...I am at a loss any ideas

12 Answers


My car is a 2005 chevy aveo it. Stalls out when take off oil light blinks off and on what could the problom


Almost sounds like it's missing. Have you changed the spark plug wires? I would pulling by one answer if you notice a difference. Could have a bad wire. Sounds like a timing issue.


Yup. It chugs a chugen


Does it cost alot to fix


New cap and rotor?


Pull your cap if you not changed it. Check inside it. See if you see white lines on the inside. Best describes and white lightning marks. Could be bad cap that's causing a misfire.


I bought the car off rightway. 5 months ago still maken payments


Sorry I was answering the questions. Above for this forum. But have you checked to make sure you have oil?


My rule of thumb is always check fluids and change oil when buying a used Alvarez that is not certified.


Ok i will do i just checked it and added a qt of oil


What cap and where is it located


Better do a compression check you could have a dead or very weak cylinder.

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