Hi, Gmtruckguy, got good news for you...and NOT trying to start an argument. If it had no signs of this before engine work, you may be in luck. They probably just left the vacuum line loose from the modulator. This can be in 1 of 2 places. A short neoprene hose near the carb hooks a vacuum source onto a steel tube that goes down to tranny--it should be hooked up. On the lower end of steel tube, there is another short neop. hose that connects tube to modulator--make sure it is hooked up.
If both hoses are connected, start engine with neop. hose
loose at
modulator. It should have good vacuum; if not, the upper hose OR the tube is not holding vacuum. Find leak and repair.
Also possible, but less likely: If the kickdown linkage happened to get hooked into wrong hole in carb linkage, or maybe not hooked up at all, it COULD very well cause this so-called "overrunning" condition.
Even least likely would be the linkage needs adjusting; but the engine repairmen would not likely 'screw' the linkage
out of adjustment. Yet, linkage improperly adjusted could also cause this same condition. DO NOT TRY ADJUSTING EXCEPT AS A LAST RESORT--EVEN THEN, HAVE IT DONE BY A TRANS PRO. He'd probably charge only a few bucks--I've done all these repairs for free in the past, but was not mechanic'ing for a living at the time
.
Sam