Transmission not shifting properly

Truck was doing fine except sometimes would hang shifting from 2nd to 3rd, would let off gas then would shift fine. Then yesterday my 4 year old decide he was going to help wash carpet in my truck and flooded floor from back seats up with hose. The water puddled pretty bad in passenger floor board. Got all water out. Was going to take it to town to vacuum it out. Start out fine and about a mile half down road started slipping. Lost all gears pulled over shut it off. Sat there a min and then tried back in 1st it engaged so I shifted manually all the way to drive held until I slowed down and let off gas. Then all was lost again. Turn off. Restarted 5 minutes later. And repeated the process. If put in drive to start it would shift till going in 3 would not shift. So this process I used to get truck home about 9 miles. I go until I had to let of gas. Then stop and try again never got over 3500 on tachometer. Would never pick up good speed. About 35 was the highest. Don't know if carpet has anything to do with it. But that's the only major change.