Shake, rattle and barely roll

MUSTANGMARK55

MEMBER
2004 CHEVROLET MONTE CARLO
3.8L
V6
2WD
AUTOMATIC
140,000 MILES

I shut it off the other night, no problems, next morning I start it, really bad miss. Wont idle smooth, tachometer bounces from 1500 down to 400, pops up fast then back down again. Go to take off, it's like a car on it last draw of gas, bucks and it's really bad. Starts fine, on the highway it will smooth out a little but very often, well those of you that have towed another vehicle and there gets a little play in the chain and then it bumps you when it tightens up, that's what it does. I have replaced the MAF, Idle Control right by it, EGR, Fuel pump and filter, plugs and wires, had the coil pack checked and the brain, nothing. Ran stuff through the gas. The weird thing is, I can unhook the MAF, Idle control, and the one below it, low idle something, don't know, and its runs the same. Could this be my catalytic converter?

1 Reply

DANNY L

MECHANIC
5,648 POSTS

Hello, I'm Danny.

Quick question first.Is the check engine light on? With your car running so badly there should be a fault code stored in your vehicles computer.If you don't have access to a code reader or scanner most auto parts stores have a tool loaner program and can rent you one. Here is a tutorial that shows you how to check fore fault codes:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Some places like AutoZone can check for free.After performing this please get back to us with the code information and then we can properly diagnose the issue.Hope this helps and thanks for using 2CarPros.