2002 gmc sierra 2500hd Tranny hard shifting

[jakeeallen]

I have a 2002 gmc sierra 2500 hd with a 6.o liter i went through some deep mud puddles in 4 wheel drive and later my tranny is shifting hard especially 1st my fuel gauge is reading 1/4 more gas then i have. i replaced pnp switch on side of tranny un hooked batt to reset codes cleaned mass air flow and air filter. Givin when i went through all the mud i never got stuck or had to be hard on the truck i have 109000 on it and never had a hard shift to it