1996 Jeep Cherokee Bogginh Problem

A month ago I sent my car for inspection and they called because they couldn't get it to start. I went up and worked and worked at it till I finally changed the spark plugs and it started right up. A week later it starts spitting and sputtering when your driving between take of and 35mph. If you can get over 55 mph it stops. Now it has developed a new problem in the same line. It starts and runs great till it gets warm then it bogs down as soon as you hit the accelerator. I changed the distributor, coil, router, wires, fuel filter, rail and injectors. The only thing we haven't changed is the fuel pump. There was some water in the filter and we blamed it on bad gas so we drained the tank and it still does it. Please help. We don't want to keep putting money into this that aren't making it better. Some day when we figure the old girl out she ought to run like a champ. Its a great car and we have never had a problem. I know its old but it's like brand new. We just want it fixed. Any idea's would be appreciated