Startup idle surge
 

hey, got a 87 mustang with a mass airflow conversion. for some reason every time i start the car from a cold start (first start of the day or just the engine is cold) it starts up just fine. but when the engine is warm or hasnt sat long enough, it starts okay at first glance. then it starts surging from 1500 rpms down to almost bogging out. sometimes it'll even itself out and have a normal idle of 800rpm. but most of the time it will almost bog out, then shoot up to 1500 and fall right back down, usually dies out if i dont give it gas(which usually doesnt help anyway)

thanks

Check vacuum lines, then check the Idle Air Control, see if its doing its job. If not i would start looking at the tps voltages to see if they are in range.

Sorry, I know I'm dragging this outta the depths of the abyss, but my wifes 98 V6 is experiencing this exact problem.

We've replaced; IAC, TPS, COIL PACK, FUEL FILTER, PLUGS, CLEANED THE MAF....we've checked the EGRand it is functioning properly, there do not appear to be any vacuum leaks.....

Was this guys problem solved? Help please. Thx.

Could be injectors or fuel lines. Run some seafoam through the gas and see if that helps any

We've tried injector cleaner.....not sea foam exactly but a cleaner...even tried some E10 neutralizer to no avail.....