I have a 87 f150 351W with the holley made factory 4barrel carb. I just rebuilt the carb afer buying this truck. The owner before me was an old guy that took really good care of it. But he got a new f250 and let this one sit for about 3 years before selling it to me. I have changed the oil and as I said above rebuilt the carb. It is running great unless you let it sit for a while at an idle it starts to run rough. And then when you take off real fast like as if to spin the tires and take off real fast. Not brake torquing just punchin it from a stop. It runs fine for a few minutes afterwards and then it starts to die unless you keep your foot on the gas and force it to keep running at witch time it runs fine until you let off the gas and then it acts like you are running out of gas and dies. Any ideas that you have would be awsome. I am thinking that maybe it has to do with the float adjustment in the carb but I am unsure and seeing as how it is best to adjust the floats when the carb is apart I thought I would sign on here and see if any one had any ideas. Thanks for your time Gus

 

I don't know mich about carbs, but it sounds like the float might be sticking.

 

fuel mixture could be off too, i dont know a whole lot about carbs but my 72 cheby hated life if everything wasnt set just right

 

Toss a can of Seafoam in the tank if your unsure of the gas quality. New fuel filter. If it's new, back flush it & see what comes out.

It only took rebuilding 1 4-barrel Carb to cure me of rebuilding. Took it into a carb shop to dial it in afterwards. Had it close but not quite.

May want to run error codes scans to see if you have an active code curve ball or hidden in the continuous memory.