04 Explorer, with 13,500 miles, has already had some sensors changed, and the shift sileniod replaced, computer reprogrammed, and also had the additive into the transmission flluid. Yesterday, after driving for 20 minutes, I shifted into reverse, and it took about 5 seconds to finally go into gear with a harsh thunk.

Sometimes while going through the gears, it dosent shift right either.

It went into the dealer today, they pulled out the transmission and are looking inside it.

Anyone have any thoughts as to what may be wrong? Or things that I should make shure they check?

Thanks