Uneven Idle is getting progressively worse but cannot find the cause (Fuel Pump / Injectors?)

[AC95]

Mine idles strange too as RPM is falling down to idle after stopping at a red light. It stumbles and makes me think Is it gonna stall? Then I put it in neutral and it evens out. I’m thinking transmission or torque converter.

 

[Dustin Jackson]

My fix for the sloppy idle was to raise it to like 600 or 650

 

[SNES Avalanche]

My fix for the sloppy idle was to raise it to like 600 or 650

Raised my idle and it helped a ton but it's still there.

I've basically accepted it until I feel like doing a full tear down to discover the issue.

 

[Dustin Jackson]

Raised my idle and it helped a ton but it's still there.

I've basically accepted it until I feel like doing a full tear down to discover the issue.

@SNES Avalanche Last thing I would suggest is try running 91 premium gas for a month and see if that helps. With the colder months coming we have the weather against us but I swear that premium makes mine idle smoother.

 

[Foggy]

It will idle better with the 91 octane (on the 6.2L).
The reason is that it goes to the HIGH octane tables on the spark tables
As soon as it detects "knock" it will then go to the low octane tables.
The difference in timing is subtle at some points, but around the idle area
it's about 2-3 degrees of spark timing , so that could def make the idle a bit different

 

[swathdiver]

Crummy idle can often be attributed to poor quality fuel and spark plugs that are gapped wrong. There are other reasons like a dirty throttle plate.

 

[kbit]

I'm thinking vacuum leak, he could rev up the motor and watch the short term trims and see if they drop...if so he likely has a leak. If he can't actually visually find anything he might need a smoke machine.