After first starting, my IROC does not run smooth at all until it is warmed up and then it runs fine. It backfires through the intake and does not run smooth at any RPM. Then when it warms up, it runs perfectly.

Tim

 

With all the engine modifications you've done, the stock software is probably having a tough time accomodating. On startup you're running open loop, where the computer isn't sampling the O2 sensor or making adjustments.

I'd get into the DIY_PROM forum and *FIRST* learn how to read the data from your ALDL using a scan tool or laptop PC. This will show you what's going on, probably way lean in open-loop given all the extra airflow you now have.

 

Whats your fuel pressure set at?

 

check for vac leaks .....the ******* way works for me. very carefuly (not around old spug wires ) spray carb cleaner on the intake area if the idel changes you have a leak