1974 914-1.8 bad idle after initial start
 

My 914 with stock 1.8 FI starts up fine with a high idle of 2000 rpm. After about 30 sec. the idle drops and engine stalls. I have changed the gaskets at the oil breather base (oil filler cap). Aside from possible air leaks what is the proper method of adjusting the idle and fuel mixture? Do I need to get an exhaust gas analyser to set the mixture correctly? Adjusting the air screw on the throttle body doesn't seem to help.

Any suggestions would be welcomed.

Tom