22R running crazy.....help

[long90]

I have a 1989 pickup with a 22R 4-cylinder 2-barrel carb, manual trans. The problem I'm having is when I start the engine it runs ok but once the fast idle cam disengages the engines starts to idle really rough, shaking violently sometimes. When I accelerate its fine but once I let off the gas the shaking starts again. I've checked the vacuum lines, air filter, pcv valve, thermostatic air cleaner, ignition timing, sprayed the carb with cleaner, and replaced the egr valve. I then tried to set the idle speed at 700rpm but it continues to jump up and down randomly between 600-800 rpm, as well as shaking. Does anyone know what is wrong?

[mikes451]

Maybe a vacuum leak somewhere. Also check the condition of your spark plugs.

[Big Flick]

I would say replace all of the spark plugs as well. Maybe even the fuel filter or something like that. Maybe the truck isnt getting enough fuel to the engine. I dont know but changing the spark plugs is a good idea.

[fourwd1]

Adjust the idle mix.

[motolane]

I had the same thing happen to me, my daily driver is an 87 toyota with 22r. On the carburator there is a little diaphram called the auxillary accelerator pump diaphram, designed to help a cold engine get a little more fuel. mine had a hole in it and my idle and fuel mileage went to crap. Basically it was dumping fuel in there all the time because of the hole. I just plugged the vacuum line untill its warmer & I can change it ! its runs great.