RPM goes up & down
 

My buddy has a 90 civic with a 1.5 in it he fix lil things in it now the engine rpm goes up & down 1000 to 1500 or 2000 sometime what cause this to do that any help will b helpful

Make sure the radiator is full. (idle speed is based on temperature readings from the cooling system) Check in the radiator itself when the engine is cold, not just in the plastic tank. Make sure the throttle cable goes slack when no one is pressing the gas pedal.

Ok we will check it out that

what my said.

my car does the same thing since i took out the thermostat. (in an attempt to alleviate the problems of my head gasket on short drives to school everyday -_-)