bad backfire
I change all idle related tables to 1200, car wont idle, like it has major exhaust leak. the motor is new from the machine shop. I checked for vacuum leaks and found none. I run two driver side valve covers with no fresh air ports or pcv. I have a breather in each oil fill hole. The intake is completly capped off. Last thing i want to try is changing the crank position sensor.
Just throwing things out there that could cause your issue. There are probably a few more, but I can't think of any right now.



