I have a 99' Z71 with 5.3L and when you go to take off it starts to putter like its gonna die but if you take your foot off the gas it stops and then it does it like 5 times and then it takes off normally. Also when it rains the main belt starts to squeak but only when it rains. Can anyone help me with this issue?

 

The sputtering could be:

1. MAF need cleaned
2. Clogged fuel filter
3. Bad plugs
4. Fuel Regulator

Try those in order, one by one, and see if it solves your problem.

The squeaky belt:

1. If the belt is fairly new, take small packet of grease OR A SMALL dab of regular grease and put it on the belt, both sides.
2. Otherwise replace the belt.
(I have the same problem, belt dressing only worked for a week or so)