Chevrolet Repair: Engine losing power at operating temp, cab chassis, engine temp

Question
Hello, I have a 1994 GMC C 3500 1 Ton Dually cab & chassis 2 wheel drive with a 7.4 big block /with a 4 speed auto.The problem I have is that when i get it up to running temp, about 190/200 degrees, it starts to lose power,so i pulled over off the road,put it in neutral.and it won't even idle,just stalls out,i hit the key again,and it will start right up,but starts to run rough and stalls again.If I let it sit for about 10 minutes,starts right up {engine temp has dropped down}then i drive about 1 mile it does it again. When i drive off when it is still cold{after about 1 min warm up,it will run excellent,then as it gets to about 200 degrees,it all starts again.I had to replace the in tank fuel pump,fuel filter,air filter,dist cap.Lots of fuel pressure.Basically it runs great until it gets up to temp, then dies out.No codes showing up [OBD1]Could it be some sort of temp sensor that won't show a code? I have been working on cars for about 30 years,but i am not up to speed on the new electronics.I am old school,carbs and older stuff.Hope you shed some light on this for me. Thanks Geoff

Answer
Hey,

 You may have a bad ignition module.  They can be sensitive to heat when they begin to break down.  The fact that it begins to run rough before it quits points to something like the ignition coil though.  Make sure the coil tower has no white fuzz on it and check it for cracks.  

Wayne