94 Grand Cherokee misses about half way up.

I have the same problem as "1998 Jeep Cherokee misses about half way up to normal temp". My 94 jeep grand cherokee starts fine except when it reaches about 140 150 then it will miss badly for 30 seconds or so and then run fine until it cools all the way down. I have no codes and have checked all the sensors and replaced the O2 sensor. I have also replaced the injectors. I have had a scanner on it for the last couple mornings and the only thing I see when it misses is the injector pulse width goes higher than it should by about 2 ms and the timing goes 10 deg higher at first then gets erratic as it continues to miss. It started happening out of the blue about a year ago.