I have a 1993 Jeep Grd Cherokee 4.0 liter 155,000 miles. I seem like when it gets hot, it starts to slowdown and sparkrattle. If I am running down the road and it decides to do this , I can shut it off and after a while it will run OK. It never shuts off but it will only run about 20 mph. Like I said it spark rattles terrible and is so sluggest. Any ideas?

Hmm.. Ignition coil/module overheating.. If that was the case, your truck should stall. That truck shares a lot of parts with other manufacturers, so there is plenty of after-market suppliers that can provide economical parts, but they may come with a limited life. Try acoil (that is usually the easiest and cheapest start ( then try it. The ignition module and/or pickup should be referred to someone experienced with that wort of thing. Ask for references and credentials...

I have a 1993 Jeep Grd Cherokee 4.0 liter 155,000 miles. I seem like when it gets hot, it starts to slowdown and sparkrattle. If I am running down the road and it decides to do this , I can shut it off and after a while it will run OK. It never shuts off but it will only run about 20 mph. Like I said it spark rattles terrible and is so sluggest. Any ideas?
Problem was clogged Catalytic converter.