I have a 90 302 5.0 liter EFI. A couple weeks ago, out of the blue it started surging like I got bad gas. So I switched to the other tank, same result. Replace air and fuel filter, as well as the pcv valve. Again, same result. Took in to my mechanic and he said no vaccum leaks, egr valve fine and fuel pressure at upper end of specs. He found one of the battery terminals broken and dirty. Replaced and he said the computer can sometimes cause the surging because of the loose connection. So 2 days later, starts surging again. Any suggestions as to what actually may be causing this? Thanks

 

Welcome to the site!

Haven't heard of a bad battery connection causing a surging problem - but I suppose we all have our unique theories and experiences on problems.

Suggest to pull and to inspect the Idle Air Control (IAC) solenoid. For our model years, these tend to gunk up, causing erratic idling problems. A little TLC with some carb cleaner straightens things out in most cases.

Was the fuel pressure staying relatively constant? I could see where widely swinging pressures might cause some issues.

 

I am leaning towards the IAC and throttle body being gummed up too. Whe he unhooked the battery he reset the computer.

 

Thank you for the welcome and the response. This will cause it to surge while driving? I also looked in my repair book, is it called something else? Thanks