Ok, so I replaced the spark plugs on my carbed '86 Toyota 22R today.

It starts up and idles better than it did before, and even sort of smooth!
UNTIL I blip the throttle. It revvs up great, but when the revs return to idle, it goes way down until it is barely popping over and I have to keep blipping the fuel or else it wants to die.

I'm positive it's running rich, but besides that, I don't know. Black/grey smoke out the back that stinks - maybe like unburnt fuel. It's not white or blue - definitely grey-black. Also, sooty plugs after just a few weeks in the engine.

Any ideas on what could be causing the weird idle drop after the throttle?

[Edited on 26/5/07 by millenniumtree]

could be a small air leak, or if its only done it since you have changed the sparks, possibly spark gaps?

Quite possibly a vacuum pipe that has been disturbed whilst the plugs were fitted, which is now causing an air leak.

Well it ran even worse before I put the plugs in.
I don't even think all the plugs were firing before (way bigger gap than the new plugs). It sounded like a harley davidson. pop pop pop - pop pop pop. as if one cylinder was dead. I tested the compression, and all cylinders are the same.

New plugs = much smoother running, until I blip the throttle for the first time, then the idle goes to crap.

I didn't touch any of the vacuum lines, although there may have been a leaky line all along. I'll have to get the water mister out and see if that changes anything.

While it was idling nicely after starting up (high idle?), I got a look at the fuel sight glass, and it is right in the middle where it should be! So the float is good!

I'll test the vacuum lines but right now I'm thinking it's a sticky choke, or that the idle is out of whack. Any other ideas or confirmation on this?

[Edited on 26/5/07 by millenniumtree]

Sorry I have no idea.
Of course, I have the 22RE.
I would like very much to know what happens to all the hoses going here and there, which were supposed to run things like the Air Conditioning and Power Steering, and won't be necessary in the new car. Also, what happens to the holes left if the hoses are not attached to their original places? There are a lot of them, coming off the EFI plenum, most of which I can't identify, even with the Service Manual.