Johnsoline

So this problem exists, can't tell you much about it. Anybody have any ideas? Thanks.

Eclair

When my truck came back from the shop (engine was poorly put back together) it had did the same thing. The issue with mine was they didn't hook up the fuel lines securely to the engine, so it was starving for fuel as a lot of it leaked. Think it'll be the last time I send my truck to a shop for motor rebuilds. But besides that, I'm really not too sure why it would be idling like that. Let us know if you find out the cause of bouncy idling.

Wilmeth88

Did you also replace the afm With an aftermarket one?

Johnsoline

Afm?.

Co_94_PU

iTrader: (-1)

Afm (VAFM), air flow meter.

Start with a visual inspection, does everything look like it's plugged in, to the right spots, and firmly attached.

Go over the intake piping checking for cracks and other sources of air leakage.

Back the idle screw out untill it will start and run without moving the throttle pedal, make sure to keep track of how many turns this takes your going to put it back where it was at some point.

If it doesn't start and run before the screw falls out in your hand (make sure it has a good oring if it does come out), put a jumper in the fuel pump diagnostic port.

At this point it should start and run. If it doesn't you missed a connection somewhere, (a vacuum leak, likely the idle air bypass hoses), the fuel pressure is not right, or you've got a bad/pinched wire somewhere.

Once it's running without someone on the throttle, at about say 1000rpms. Verify the ignition timing is to spec (jump in plase.to set base timing) and start backing the idle screw to where it was while watching.

This all assumes that the engine is mechanically sound and has proper valve timing..