did you end up finding up what was wrong? im having the exact same problem in my 1997 k1500. and its actually ironic because i just did a full rebuild on my tranny about a month ago too but i dont think thats the cause, it might be a faulty PCM

 

My 98 did this laat may. My code was a p0305 and after tossing a cam, lifter set and lots of valve adjusting. It turned oit to be a burned/ slightly bent exhust valve. Caused by. Hard run then hard decel then hard run caused a hard lean out and heted the **** outta the valve. But. To figure if your trans is the culprit, does it miss in neutral? Rev in neutral does it miss?

 

I wonder if a crank relearn would help here?

 

I had the same problem with mis fires. Turns out that the #7 injector was clogged. Just remove injector, spray with brake cleaner and shake the stuff out of it. It should be a bunch of carbon and crap. Re-oil "O" rings, and re-install.

 

i had the same problem on my truck. changed to new spark plugs, wires and fuel filter, cleaned out all injectors and still had the misfire... at the end of it, it was a bad #7 ign coil... and now that i think about it. it all happened after my tranny went out and i put in a new rebuilt tranny. weird... checkout ur ign coils...