88 f350 stalling

i bought a 88 ford f350 with the 351 efi. im having a problem keeping it running. it will start eventually after repeated attempts to crank it over. it will run for maybe a few minutes if you play with the gas. if you let it idle it will die after a few seconds. ive already replaced the fuel filter, plugs, wires, distributor cap, and rotor. not sure where to go next. any help is appreciated please.

Check the fuel pressure, your fuel pump may be trying to die.

thanks for the idea, i think you're right. ive been trying to use the front tank because its new and the truck is having the problem on that tank. i switched it to the back tank and now its fine on that one. i had to replace the fuel filter because the fuel filter clogged on that tank though. so im assuming now its the pump on the front tank. on the switch up is front tank down is rear right? i dont have the owners manual so im not sure.

I used to have a '77 F250, the switch on its dash said MAIN and AUX, Main was for the back tank, Aux was for the front tank. Mine had a mechanical pump (engine driven) that sucked gas from both tanks so I'm not sure how your's is setup.

its two electric pumps as far as i can tell. the only thing my switch says is fuel. it does say which tank was which. so was up on your switch main or aux? also can anyone help identify my transmission. i think it needs rebuilt. the sticker in the door says z. its a manual with 4 speeds and overdrive.

I don't remember which way the switch was, I think MAIN was down.

No idea about your tranny, I would imagine that it has some kind of tag on it with identification numbers, find them and run them through Google or ask a Ford Dealer.