If it dies when the rpm's drop below 2,000, I would think vacuum leak somewhere (old hoses crack, possible cracked carb base) of idle not adjusted correctly. As for the old gas, I'd drain the tank, wash it out (or replace it, you can get new ones for about 100 bucks), use compressed air to blow the fuel line clean from tank end to fuel pump end, place a new filter between the fuel pump and carb. I would suspect possibly the fuel pump after checking the for a vacuum leak. Welcome to the wonderful world of owning a 40 year old car....
Well, 3 carburetors and two engines later, I am still having performance
> problems with my 67 stang (stock 289). Just dropped a rebuilt (bored to 40)
> 289 in, built by a very respected (and not cheap) engine shop in town. >
> The escapade started after my vehicle sat for a couple of years (started at
> least once a month, mind you). The engine only had about 15000 mi. on it..
> I parked the car because the suspension and body needed major help (all good
> now). When I resurrected her, she was blowing much carbon, and I went
> through several carb rebuilds (Autolite 2100), which I still feel were
> correct. She would run ok for a while, then start acting funny. Like I
> would hold her at about 2000 RPM, grrrrrrrrr! for a good solid amount of
> time. Then spat spat!, shake shake! grrrrrrr! The timing was correct,
> constantly changed the plugs, fuel filter..
>
> Finally, I ordered a professionaly rebuilt Autolite from Pony Carbs in New
> York. Put it on, started her up, same thing. Then I hear this ticking.
> tick tick tick tick, in nice rythm. Sounds like somethings loose in a
> cylinder, not good. Did I drop something in the manifold? Paranoia set > in..
>
> I am a novice, so this was bold, but I tore into her. With the heads off, I
> could see even with my untrained eye, that this engine was crap.. There was
> RTV spattered on the cylinder walls, some gouges in the walls, and worst of
> all, three of the pistons were shattered (partially) from detonation
> (according to my new builders). Hence the noise, a piece of one of the
> pistons bouncing around. Phew! I'm not a total idiot.
>
> So, @*!# it! Let's get it rebuilt. Just got it back two days ago
> (different used block, as the old was bored to 60).
>
> The install went well. When complete, I primed the engine w/ oil... She
> started after jerking the distributor around a few times. Sounded pretty
> good, except for some exhaust leaks, my next adventure.
>
> So I run her at about 2000 RPM for a while. Time to hit the road.. About
> two miles away, coming to a stoplight, the car goes spat spat gasp.... > Dead.
>
> Crank crank crank.. nothing.. Crank crank crank.. nothing..
> roll roll roll... into a parking lot.. Confused, looking it over... Try
> again, still nothing.. loosen distrib nut, advance it just a bit.. still
> nothing.. wait a few more minutes. Try again VAROOOOM.. grrrrrrr.. Start
> for home... runs a bit, spat spat gasp... dead again.. Called wife...
> instructed to bring new fuel filter... replaced it, started.. drove home...
> running a bit rough..
>
> *******
> Thing is.. if I rev it up to about 2000 RPM and hold it, it sounds smooth
> for a few seconds, then starts shuddering and falling off a bit.. > *******
>
> So, could I just be dealing with bad or dirty gas?? That'll sure piss me
> off. My next step is to drain the tank, blow out fuel lines, replace the
> fuel pump, unless somebody steers me in another direction..
>
> At night my lights vary in intensity when engine revs. Probably a vlotage
> regulator problem, Right? Could the voltage regulator or other part of
> ignition system be causing the stalling, or is the fuel the most likely > culprit?
>
>
> Thanks for listening to me whine. Any help is thoroughly appreciated. >
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