inline 250 ??'s

[BAGNDRAGIT]

ok guys and gals, stumped here. i bought a 71 short step about 3 weeks ago (technically paid 1800 bucks for it) so i cant complain, mostly complete and already lowered.

anyway, i have been trying to get the truck to idle correctly since day one, i have rebuilt the carb (rochester monojet) 3 times, i have timed it twice i have replaced the plugs, intake and exhaust manifold gaskets all vac lines, wires are newer the distributor was upgraded to electronic..not by me, i have replaced the batt cables and coil as well along with a new pcv and fuel filter and all rubber line, it also thee vac moidulator on the trans. still misses at idle, i am stumped, although when i pulled the carb apart the main metering rod didnt seem to wanna seat in the seat. is that normal?? seemed too short... i am going to change it to HEI cause i dont trust the electronic setup since i didnt install it. is there anything i might be missing?? she runs great off idle, real smooth, but as soon as i stop at a light all it wants to do is start missing and die while in gear, but in park my idle is really high. i also have my mix screw on the carb turned all the way in so im leaning towards the main rod being the problem but i wanted some opinions and experiences from here.
i hope im not missing any info. just to be sure its a 71 250 i6 with a turbo 350. non ac ps anyway, its late im tired, tell me if i missed something...

also does anyone know what years and models had the 6 cyl HEI in them??

thanks in advance!