Hi

I have a 1990 foxbody drop top. The issue is so odd. The engine temp stays the same for roughly 20 minutes then out of nowhere it will just start to get hotter and hotter till it starts high revving stalling and just acting out. I've replaced almost everything but the block which is a Capri block bored over .30. any ideas????

 

I always start with the small stuff. Like the radiator cap, spring gets weak, heats up and won't hold enough pressure.

 

I Just put in a mishimoto rad. Could that be the problem? I just put in a new thermostat last week and it sorta worked.