S10 has no power

picked up this 86 S10 blazer 5 speed thought it was
pretty rare so I jumped on it. The blazer had been
setting for awhile and needed a fuel pump so I put a
fuel pump in it and drove it home no problem. Next
morning went to start it up no start just crank so I
sprayed starting fluid in it took a minute but started
up idled good. I took it to carwash below house got
the sap off it and noticed had a leak in tire tried to
make it to get air and ended up riding on rim shaking
around finally got a spare on it but now it would only
start up with starting fluid so I dropped the tank and
noticed the gas was completely deteriated with rust I
emptied it out and the gas looked like pure rust put
another pump in it and changed fuel filter and it starts
right up every time now but when you put it in gear it
moves maybe 3 feet before stalling out but but the
wierd part is if I cut the engine off and right back on
and take off in first gear it goes perfect for about two
seconds then starts bucking and jerking and has no
power I had to keep repeating this process just to get
it back home. I replaced fuel pump, fuel filter, map
sensor, ignition coil took the plugs out and cleaned
them they looked good and all were firing. I put a hole
in the converter thinking maybe it was clogged but
still doing same thing. I am mechanically inclined and
had about 13 of these things this is my second one in
manual so I would love to get it back to normal also
now it acts like it's starting to idle rough. Injectors
look like they are spraying a good cone. Could it be
the bad gas got inside the engine and clogged it up or
distributor, idle air control, possibly cracked dizzy cap,
I just want it to run good again and I have no idea
what to replace next thanks in advance you guys
usually nail the culprit when I ask a question.