My trannsmission sometimes pops out of gear it only does it in 3rd when im on a off/on ramp off throttle but the rpms are still up there and it does it in 5th when im off throttle but going slower than highway cruising speed. I've also noticed that on the shifter the gears seem to be further back then they used to be, almost like the shifter is bearly reaching it. And some at a light I'll think i put it in 1st when in fact it went into 3rd.

Any cause of what the problem could be?, and about how much is this lil problem gonna cost to fix