1990 F150 Wheeler

[ChevyGuy]

Well I figured out that my truck isnt the 2 fuel pump system, my fuel pump stays on the whole time I have the key on, also i put gas in the throttle body and it fired right up but wont stay running and when I step on it, it wants to die. Witch I think that means the fuel pump isnt building enough pressure, going to hopfully replace it tomorrow.

 

[ChevyGuy]

Replaced the fuel pump, put the tank back in and it wasnt the problem.......I still have to put gas in the throttle body to start it up, BUT it idles now, sorta, it goes from 300rpms to 900rpms and back down, it repeats that the whole time its on. I managed to drive it, but when I floor it, it doesnt get enough gas and starts to die, I can ease the throttle to high rpms.

I tried 2 different OBD1 readers, neither of them are working on my truck. I really dont know what to do now, does ANYBODY have any ideas on what I could try?

I really do not want to get rid of this truck, I wanna go through with my plans I have for it.