I have 2000 suburban 1500 4x4 on long trip it will get sluggish can push the gas to floor hard to get up to speed with it.but can reset the computer and it drives fines.anyone have any ideal what going on with it?

 

hmm. Need more info. And slow down on typing. A bit hard to read. What motor? How many miles?

 

5.3 323.144000.also forgot to put,it does this when cold in the morning too.but once get out of first gear to second seem to be fine.could this be the valve body?i don't feel any slipping in it

 

If you really think this is a Transmission problem, and not Computer related, I suggest that you run a good Cleaner in the Transmission with an eventual Fluid Change first.

 

ya it seem like a valve body maybe servo deal.i haven't notice any burn fluid smell!just kind sluggish around 10 20 30 mph then fine.i'm gonna change the fluid and check out the mag in the pan.how do I check the valve body?

 

Again, IF you run a cleaner through it first, you may not have to check the Valve Body
You should be able to tell if it's done any good before you take the pan off. Then you'll know if you need to continue. If things get better, then just change the Fluid and Filter. 90% of shifting problems are because of shellac which is most frequently created from overheating or lengthily uses of Fluid. It doesn't' have to smell burned, to have a buildup, and a very easy inexpensive fix if it works.

But, a picture is worth a thousand words...