So basically I can start my 72 F250 and drive it for 10-15 minutes. It'll run just fine. Then it will start to stutter a bit and bubble when you press the accelerator. I can take it out of gear and it will idle will im coasting, but the second i press the gas it falls flat on its face. Then it'll cut out after 45 seconds to a minute of this bubbling stuff. Then i have to coast into a parking lot then let it sit for 15 minutes or so, then it starts again and idles fine. Then it'll go about a mile at a time in between the engine cutting out. I've already replaced the fuel pump. My dad thinks there must be water in the gas. He seems to think on a really large scale though. Before we drain the gas and filter it, are some other things we could do? I'm wondering if it could be something with the aftermarket electronic ignition, or timing, or something like that. It does seem like the problem is it's not getting enough fuel, but i could be wrong.

 

I experienced the same thing with another project car that I own. It would start up cold,warm up,idle and run fine. You would never know anything was wrong until you actually tried to go somewhere. Would go about two miles run rough and quit. Wait 10 minutes,start fine and go another mile then die again. To solve the problem I had to drop the fuel tank,remove the sending unit and replace the screen on the fuel pick up tube. I also had to have the tak cleaned out. I haven't had any problems since.