car bogs down when giving gas and problems goinin up hill

i have a problem with my 02 monte out of no where the car started bogibg down when givin gas and will only go about 20-30 mhp up hill but the rpm will be around 3-4. At first had car hooked up to computer and it read egr replaced that and is still doing same thing. has anyone else had this problem or can give me an ideal what the problem might be?

Well, if the engine produces lots of revs, but there is little power to get up hills - I'm thinking the transmission is slipping.

How well does it accelerate from a stop on level ground? Will it rev high, but accelerate slowly?