Is it possible that the rebuild shop put the heat riser valve in backwards, causing excess back pressure in the manifold, causing the engine to skip and cut out and then stall when it is fully warmed up and under load? Also to run very hot- in terms of heating up the car like it never did before, and to be sluggish?
One thing I noticed when the car came back from the shop was that I no longer heard the "tick-tick" sound that the heat riser made when the car was running. The shop also complained about difficulty reinstalling the exhaust connection and that the muffler was touching the floor, which it never did when they got the car. This could be a clue.
It seems to me that the fuel, exhaust, cooling and electrical systems were the only peripheral systems that the shop had to touch to remove and reinstall the engine. These were all in perfect working order when they received the car, and the only issue was the oil fouling in the no. 1 cylinder. When I cleaned the plug, the car ran with smooth power and acceleration, because the engine was in perfect tune, and with all 8 firing, it ran like a new car.
The ignition system was now replaced twice and the symptoms are exactly the same: starts and cold idles good, but when engine warmed up and under load, intermittent cutting out, stalling, and lack of power and abnormal amount of heat through the floor.
We gotta figure this out. It has to be something very basic that was not put back correctly by the engine shop.
What do you think?