I just bought a 88 5.0 the problem i am having is pulling my last hair. i have replaced the head gaskets and water pump but it still runs hot. also when i start it up it has a rough idle up and down and then when it gets warm its fine. could that be radiator. also when i set the timing with the plug out its fine but when i put the plug back in its all messed up. could that be the distributor? any help would be great. thanks adam

 

That sounds like a bunch of stuff? Runs hot? How hot? On the gauge, half way? About that? A tiny bit less then half way is about 180 so try to guess from there? Have you checked the thermostat? Take it out and heat it with a torch or boil it in some water. If it doesn't open or it takes a long time then that may be the problem. Could be a faulty sending unit, those are a few dollars, wouldn't hurt to change that. Is your cooling fan coming on? If not, is the fuse for it blown?

Idle? Plug in the spout connector, then unplug your IAC valve, you may have to play with the throttle body stop plate to get it to stay running, but check the idle then. Those things are notorious for cause problems like that.

 

it runs in the middle for a while but then when you take it for a drive it climbs all the way to the red line and stays. the funny thing is that it doesnt act like it is over heating, no knocks and no weird sounds like you would think. i took out the thermostat, it works fine, changed the sending unit, fan is fine. i think that it is my radiator, its start to steam after only running for a few mins. i am new to mustangs so what is a IAC and where is it? thanks for your help. thanks adam