check fuel return, some needs to return to tank.
Assuming you still have the OEM filter. Is there a large flat rubber washer at bottom of filter cartride that makes clean fuel flow thru the filter and not suck unfiltered fuel thru the hole at bottom. If not, fix, blow out every line.
Remove fuel cap, apply 5-10 PSI air, preferrably with a small type compressor, using wrags, tape or whatever to seal the opening. Net is small amount of pressure to find leaks. Fix leaks. (not every fuel line leak-leaks fuel. Some suck air)
Check butterfly valve on air induction side to verify movement. On pneumatic govenor, that is your throttle. Here's a quick check to see if it is butterfly valve. Loosen glow plug and start engine. If when glow plug removed, she revs up, its not fuel... With glow plug out, it'll run more than wide open!