Thread: possible rough idle problems

I have a 91 grand prix with a 3.1 mpfi. It has a really wierd idle its running at 500 rpms and it sounds like its only running on 3 cylinders. When you hit the gas it sounds like that all the way up to 1000 rpms. This only happens when warm which is whats got me confused.

So I was wondering if they came with a fuel saver mode. If so is there a way to reflash it to turn it off? It has bad throttle response up to the 1000 rpms but past it it takes off.

lol its got that ecotech 3cylinder idle sound to it... 1-2-3-pause....1-2-3 pause... and its got brand new wires and plugs. got all new packs wires and plugs when i got the new motor in october. 60k on a 21 year old motor lol.

I refuse to use seafoam.... I'd like to keep my engine running lmao. Only the check gauges light is on and thats cuz I got a short in the switch for the gas light and the light stays on even though I got a brand new sending unit on it and pump. I dont think its a sticky valve cuz if it was it would be backfiring and its not. Just sounds like they're not firing, sputters to 1000 rpms then its gone. If it does have a sticky valve then someones gonna be getting a top end rebuild for free lmao. I got a 1 year warrenty on the motor cuz I just had it put in in october.

And no no vacuum leaks they put brand new hoses on when they put the motor in.