Bartamos......Yep, I even got new cables....but who knows, maybe the terminal end on the starter is not crimped properly and losing conductivity when it gets a bit warm. Also, the header pipes are pretty close to the starter solenoid and that portion of the battery cable. Could the heat from the header pipes cause the solenoid to not want to perform properly? But, why would this be a problem after 25 years.....and a new solenoid/starter was just put on.
I guess another thing to try would be to make a heat shield to go between the solenoid/starter and the hot header pipe.
Like you said at the end of your post, Im leaning to some kind of valve train problem. Is there anyway that the hydrualic lifters could be failing and not pushing the valves all the way open when warm? Any way to check this? Would a compression test show anything?
