Major Ledfoot Rob;106188 wroteI am up for mad guesses. Something which changes characteristics when it gets warm/hot... Coil? Ballast resistor?
Rob I replaced the coil with a spare used one. no change. ballast resistor would stop it running altogether I would think.
Rob Thanks all for the advice. Today I grabbed 6 matching glass bottles, pulled the injectors and stuck one in each... fired up the pump and manually opened the flap, injector spray patterns look fine. I left it like this for a few minutes and then compared fuel volume in each bottle. There was a maximum 4 percent difference in volume. I think that is ok. I decided to remove the intake manifold (and everything else associated with it), cleaned the manifold inside and out, the throttle and air side of the fuel distributor, replaced all of the intake gaskets and o'rings and confirmed there were definitely no vacuum leaks. Everything was dirty but seemed to be in pretty good shape. I have not got it all back together just yet but will have it done tomorrow morning. I also bought enough equipment to allow me to set up a pressure tester so I will be able to test that tomorrow too. I also replaced the distributor with a spare. the old one looked pretty good though.