Gents,

I've been scratching my head about a mildly annoying issue with my '89 Runner V6 3.0. It is one of those infrequent glitches that only occurs under specific conditions.

Some background:

When I leave work, and it is cold (in CA that is 40 F at 5:30 at night) I coast down a hill in second gear with the throttle at idle, to stay under the 25 mph speed limit on my work site. The idle will surge up, down, up, down about 800 RPM. The truck responds to this surge with a mild lurching. If I put a little throttle into it, it goes away. After it is warm, never occurs.

Things I have checked:

I have checked and rechecked the idle position sensor.
I have looked high and low for a vacuum leak, spraying starting fluid around connections, etc.
I have checked all of my electrical connections, they are tight.
All of the plugs, wires, cap, rotor are new, less than 5k miles.
Injectors were cleaned/rebuilt last spring when I rebuilt the motor.
Valve adjustment done a month ago, three valves were slightly out of range, shimmed them back in.

I do hear an exhaust leak somewhere and have not tracked it down yet.

Opinions?

Thanks,

Mike