I have a 89 pickup, 22R 4 cylinder, 2 barrel carb, manual transmission. The problem is the engine is acting crazy. It idles extremely hard and shakes violently, also it jumps up and down between 600 to 800 rpm, it wont hold the 700rpm as specified. I've checked the vacuum lines, air cleaner, pcv valve, ignition timing, thermostatic air cleaner and sprayed the carb with cleaner. I also replaced the EGR valve. When I start the engine it runs good, then after the fast idle cam disengages it goes crazy. When I accelerate its fine but when I let off the gas it jumps around again. Does anyone know what I can do?