comp. losses power with excissive heat

[peewee22]

I have a2001 F350 with 6300 miles. Last month when pulling a trailer then truck bucked and died (like ran out of fuel) replaced the idm with a reman and it started right up. problem now is running by itself in temp above 90 degrees or so or pulling a trailer anytime and producing extra heat the water n filter light, wait 2 start light,and service light flickers on and the truck will go to an idel if u let up on the peddal then u can go again,it does not set any codes. We tried another idm, different computer, cam pos sensor,even tried a hot wire direct 2 computer(buy pass the key switch)still same problem. Truck will run great as long as there is not exstream temp. under the hood. Where do I check from here( besides C-4 explosives)

[peewee22]

I fixed problem buy putting new alternator on and running a ground wire from batt. to the fire wall. Haven't had problem since