Really rough idle, misfire and backfire

CRISTY BOLDEN HUMPHERY

MEMBER
2000 CHEVROLET TAHOE
5.3L
V8
2WD
AUTOMATIC
200,000 MILES

Having a really rough gulping like (lol) Idle and revs up on its own while in park. When put in gear it almost shuts off if I don't hit gas, and shuts off sometimes when braking to make a turn. While driving it has power loss barely wants to go and backfires the whole time. I have put a new Throttle body, MAF sensor, MAP sensor, EGR valve, new plugs and wires. Replaced air filter, checked wires everywhere, nothing has changed. When I put new spark plugs wires on it seemed like it got worse. Fuel pump comes on. Any Ideas would be greatly appreciated.

1 Reply

KASEKENNY

MECHANIC
18,907 POSTS

We need to check the base engine operation. That means we need to check the vacuum leak and compression to start. Also, we need to check for codes and see what is there.

Here are guides for all that we need to do:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

https://www.2carpros.com/articles/how-to-test-engine-compression

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

Let's start with this and go from there. However, I suspect we have a larger engine issue so we need to make sure the compression readings are correct.

Let us know if you have questions. Thanks