1988 Jeep Cherokee what is it

I think I understand what your asking. First, the gasoline splashing is probably the result of the O-Rings being bad or not installed properly when you changed the rail.
They can be bought separately in a kit. Try changing ALL them on each fuel injector. There are 2 per injector, one for the top end that goes into the fuel rail and one that seats on the bottom end that goes into the engine. There is also one at each end of the fuel rail. Also check the plastic "quick-connect" pieces that connect the fuel lines on each end of the fuel rail. These can go bad and the O-rings inside them can break and leak.

With your overheating, thats an easier one. These model Jeeps have a silly radiation system. ALL the pressure is contained in that plastic overflow tank and it's cap. Ive had to replace the cap twice and tank once. They are VERY sensitive to losing pressure if the cap is leaking even ust a little! And its so small a leak that many times you dont even see it.

Try getting a new Cap first, and inspect both hoses that connect to the overflow tank to ensure they're not bad/cracked/loose. If that doesnt work, get a new overflow tank. I had to do that once because the plastic threads on the old one were worn out and the cap couldnt seal right.

Good luck!