My 87 ford ranger 2.9l will not start correctly after engine is warmed up?

The engine will start ok if the engine is completly cold. When you turn it off after it has warmed up, you have to crank it for about 10 seconds then mash the accelerator it will putt and then finally start. I've been told it might be the fuel pressure regulator. I do not want to go buy a bunch of parts for a 20+ year old truck. I've replaced the coil, spark plugs/wires, air cleaner. There is multiple sensors that it could be i just don't want to buy them all. PLEASE HELP!!!!