Ford Repair: 1976 Ford E350 Van stalls when shifting to Drive or Reverse, ford e350 van, ford 351w

Question
My 76 Ford (351W/C6) starts and idles fine. Can start in either park or neutral. As soon as I move the gear selector to drive or reverse, it stalls.  Can't give it gas fast enough to keep it running.  Advice?  Thanks

Answer
Eric, have you done any work on the vehicle recently?  If you have, then recheck everything.  The first thing that came to mind it that you have a vacuum leak.  You might check the transmission modulator valve and see if it is covered in transmission fluid.  A bad modulator valve might cause the vehicle to stall.  Maybe.  When the vehicle is running, can you hear any "hissing" noises?  Also, have you made any adjustments to the idle?  You might try taking the idle up.  It should idle around 900 rpms, if it is a stock motor.  The only other thing that comes to mind is the carburetor.  It might need to be rebuilt.  Try spraying some carb cleaner through it and see if that helps any.  If it does, then your jets might be clogged, or you might have some water in the bowl.  Run some pour in "Seafoam" and some "Heat" through the gas.  You can pick these up at your local parts store.  If you can think of anything else that is going on with it that might be useful to know, write me back.  I hope this helps,  Jason