My 89 iroc 350 tpi wont stay running. Ill start it idles high then idles down and idle super low then cuts off??? If i want it to keep running i have to give it gas. Before i put headers/y-pipe, cat, and catback on it just idles high its been sitting for about a couple weeks now it doesnt wanna stay running unless i have my foot on the gas.

Have you checked the TPS setting? Are you showing any trouble codes?
Sounds like TPS or IAC but not sure until we get some more info.
When you say it idles high, what RPM?
Pull the codes and post your results.

I cleaned the iac and throttle body and now it idles good but still surges alittle bit it throws no codes.

possible vacuum leak for the surgeing ?