87 Cherokee intermittenly runs

So after doing my fair share of searching on here and Cherokee Forum, I still cannot find the exact answer to the problem I'm having. I have a 1987 Jeep Cherokee Pioneer it's beat to hell and has over 300k mi. on it so I'm not surprised things are acting up, regardless. My issue is my jeep started by intermittently loses 100% power for about a second then runs again. Lately however I have a wire coming off of the Starter Motor Relay that starts glowing red hot and melting the coating around it and my jeep wont run. The wire will get red hot with the key just in the on position. I dont know what to do anymore, I love my baby and would love to try to keep her running at least till I can find a better cherokee. Anyone got any ideas? I was thinking about replacing my hot leads and grounds off the battery as well as adding a battery to chassis ground. All suggestions appreciated. Thanks in advance guys!

Job #1 is to fix that wiring issue before it starts a fire.

You need a meter, a wiring diagram and some ability to use both to figure out what is going on there. Could be anywhere up to and including the ignition switch.

Never hurts to freshen ALL of your grounds and electrical connections. RENIX vehicles are especially susceptible to ground issues.

I'd love to get ahold of a diagram of the wires that come off the Starter motor relay so I know what I'm frying and why. I replaced the relay and it let my jeep work for 3 days then took a crap again.

I agree with birchlakeXJ. You need to get a volt meter and start tracing things back. Older vehicles = wiring issues. I have an 87 4.0 Renix and have had to troubleshoot many issues myself. In particular it should like you have a hot wire shorting out. I have a service manual/wiring diagrams in PDF if you are interested. Send me a PM if interested.

I had that exact problem once. The O2 wiring harness wires got hung up and ran into the exhaust pipe, shorting the O2 heater wire to ground. The only interupts in the path were a high amps fuse link at the starter solenoid and the relay. My first clue was the voltage meter on the dash crashed to left side. I pulled the relay (which let me drive with out the short) and drove home...till I later found the shorted O2 sensor wires.