krisjeep6

I have some issues with my ballest resistor at times. My 1990 jeep xj has approx 238xxx miles and runs great but sometimes it starts running very rough and starts knocking. When it does this I have to change the ballest resistor to the back up in my glove box and I fire it back up and it runs great. I have tried locating the resistor off the inside of the fender and down lower where it can get air movement to cool it some. The resistor gets very hot and I assume that is normal and how it works; but when it gets too hot it just resists to much and does not power the fuel pump enough causes the engine to run rough. Where do you think my problems is. Wiring, fuel pump going out? Just bought two OEM resistors that I use. May try to locate the resistor by the electric fan that I have running at all times engine is to keep it cooler. Easy fix since I have pinpointed the problem but strange since sometimes I can drive 60 miles with no issues or 2 miles. Usually notice the problem after a drive, kill the engine, restart and runs rough. Thanks for any advice.