[Pandasar]

I have a 1990 Chevy C/K 1500 4X4 with a V6 and it just started to backfire constantly.

for a little bit after the first starting of the day its fine

then when i go to drive again it seems like it is loosing power going into
1st gear and will putter for a bit, then when i shift to 2nd gear it looses power and starts to backfire until it get going, 3rd, and 4th gears do the same thing.

I had recently just had the valve seals done and i know it needs a major tune up I have also noticed that the cadilac converter starts to stink going up hill on the freeway

i really aprciate any help