Still missing, I've added Sea foam to gas for treatment , changed plugs, wires,rotary, and disturbutor cap, changed oil and everything, andsuggustion.

 

make sure you plug wires arent crossed over one another the spark will travel from one wire to another and cause a miss fire

 

this only happen when I'm putting load on it, like when I put it in gear, it is a 5 speed trans, 87 5.0

 

this was happening before I changed my plugs , the car set for abour 7 yrs, I finally got her running, I also cleaned the trottle body, its also fuel injected.

 

hmm i dont know thats all i can think of you might have a bad fuel injector put a prob light on the injectors while the car is running and see if its firing fuel right

 

I f the car sat for a long time it could have a sticking valve or broken valve spring?? I'd run a compression test first to see if there are any major differences between cylinders and then if all checks out....you could perform a cylinder leakage test to see if valves are sealing tight.....also inspect all wire harnesses to injectors ...when a car sits for a long time expecially outside, rodants like to make bedding out of the wire harness