rough idle -- help

[CHAN WEN YEN]

I'm repairing a 1990 Acura Integra with the 1.8 l engine (no MAF sensor)
. The engine has a rough idle when the ambient air temperature is below
zero and the engine is warm. The idle will dip as low as 500 RPM when the
brake is applied (the car is not automatic) and will eventually settle
just below the normal idle (normal idle - 750). The idle will also
fluctuate +/- 50 RPM @ idle. During periods of rough idling the 
vacuum fluctuates rapidly +/- 1/4 inHG about 19 inHG.

	I have changed the air and fuel filters, the spark plugs, the
distributor cap, the PCV valve, reset the base idle & advance, set the
valve lash, removed the carbon from the intake manifold, throttle plate
& valves and used about 4 doses of fuel injector cleaner (motormaster
brand). After changing the air & fuel filters the idle was smooth &
stable for about 5 min.

	I would appreciate any advice. Thanks.

WenYen Chan
chanwe at ecf.utoronto.ca


p.s. has anyone considered using 1) a nitromethane/methanol fuel blend
(ie: model airplane fuel)? 2) a scuba tank with a high flow regulator
feeding the intake instead of turbo.