I am getting late shifts in my 300D auto tranny. I need to crank it out to get it to go to fourth, where it will stay momentarily, then it will jump back to third on the highway. This is a sudden thing; wasn't like this before. Fluid ok. Could I have dislodged a vacuem hose or something? I just changed the oil, oil filter, fuel filters and air filter. Downshifts fine (in fact, that's the problem). No slippage yet detected. Just seems to be off all of a sudden. I checked the forum on this and found nada. Thanks for any help in advance.