85 ford F-150 5.8 carb was rebuilt and ran awsome

I hate to disapoint you but the mixture screw will not clean out your carburator. It is vary easy to rebuild this carb I have an 85 2.8 2 barral have rebuilt it 4 or 5 times for about 30 dollars for kit its a Rodchester .So get the kit get some brake cleaner with the tube to spray through the passages its basiclly a power valve and new gaskets take it apart and clean it and it will work like new evertime

Are you saying you think it is getting too much fuel, or not enough ?
Could be the choke or something inside the carb.

partially blocked fuel filter or clogged injectors. Good place to start. Also, does that truck have a coil for every cylinder?

float in carb not set right nor are the air jets

Possible things to be considered: Float level too high, needle has a bad seat and won't shut off, vacuum leak (either internal or base gasket), choke not properly adjusted.

My money would go on a carb. rebuild kit (but only if you feel comfortable attempting it) it's not all that difficult, but you MUST be (1) an absolute nut about cleaning it all very well, and (2) the various gaps, clearances, adjustments, must be made with excruciating precision.

This will be a lot cheaper than a rebuilt carb., and you'll get the satisfaction of doing it yourself.

While you're at it do a general tune up.....plugs, points condenser, wires , air filter, PCV, etc.

Check the two screws / pins on the side connected to the air / gas flow levers. The screws go into and out of the carb and / or rods itself. Just play with it and hope you didn't leave anything out!

Check all vacuum hoses for cracks and disconnections. Also check pcv and egr

it sounds as if you have blocked jets cause what you have said it seam that when you had the tank repired you had some dirt get into the fuel system whick blocked the jets you have to get the carb cleaned and replace the jets and then have the carb set so the emitions will be to law specks

well it could be that you need new spark plugs definatly new piston rings hmmmm was it hard to start before you put the new carb on?

If it was a dealer, go back & have him scan it for fault codes. Usually cheaper to have it scanned and replace one faulty part, than replace 5 parts before you hit the right one. Autozone & PEP boys apparently will scan for free if you bought it private.