It will stall or not start(no crank) on very hot days, above 85 degrees F

My 3.0L 1988 New Yorker intermittently won't start with the key and I have to jump the starter posts, how do I fix that? The vehicle runs a little rough, seems to have a misfire under load around 1500 - 3000 RPM, if it is abused(hard acceleration after another) it(can stall and) will refuse to start no matter what I try.. I changed the computer 2.5 years ago which made this happen so I re-installed the old one and it started and ran fine for a year and a half. I changed the ignition cylinder 3 years ago when I found one day my key would not come out(which also led to my breaking the tilt trying to get the key out by hand). I bought the car 4.5 years ago and replaced the valve guides and intake seals/gaskets, water pump, idler pulley, timing belt. I was not able to remove the EGR and install my new one as I did not have a torch and the nuts are literally round. The car will not crank using the key intermittently but it will start if I jump the starter, the fuel pump cycles, the thermostat is new, I still own the other ECM but the car performed the same with it which is why I put the old one back in. I suspect a short/faulty relay somewhere in the cranking circuits, what should I do and who has a crank system wiring diagram?