hi i got a B20 with a gsr head, ill start it up and it will rev up to 3500 rpm then drop to 2000rpm and it will drop down to 1000rpm and go back up to 2000 and drop to 1000 and go back up to 2000rpm and so on and so on. it doesnt ever stop. i have no idea what it is please help.

 

have you checked and cleaned the IACV? check for vac leaks ?

 

how would you chech the th IAC?

 

12 volts and listen for a click