hi.
i'm having problems with my 78 f150 with a 300 motor & a 4 barrel holley, it all started with a bad accelerator pump so I thought, replaced it & it still fell on its face everytime i gave it gas. so i replaced the intake & exhaust manifold gaskets, compression tested it #145, new plugs, new plug wires, dist cap, rotor,& still no help, so i had the carb rebuilt by a local mechanic. & that fixed that problem, now the truck run like crap, i have to pull the choke in to start it, even when the truck is warmed up. the engine dies every time i'm moving forward & pull the clutch in, except going up hill & reverse ( manual trany)then the engine rpm increases. so i take the carb back to the mechanic & he resets the floats still the same thing. has anybody ever ran into a situation like this? i think he screwed up the carb, he thinks it a vacuum leak. i cannot find a vacuum leak ( carb cleaner) the vacuum off the carb is #14 if i disconnect the pvc valve the vacuum goes to #18, the fuel/air mixture screw on the driver side of the carb i can screw it all the way in or all the way out & it does nothing, the other one is 2 1/2 turns out for max vacuum ( #14). also as soon as i pull the vacuum advance hose off, the engine dies. and i notices when i pull the float sight screw off,there is a vacuum there & the engine revs up. which shouldn't happen. i hope this makes sense to everybody.

please help this thing is driving me crazy

 

Your mechanic was right.

 

If you still have a factory egr carb plate, maby it's burned out underneath ?
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