'09 SF 3.3L with120K miles. Believe it's the 5 speed automatic. Two weeks ago shifting into reverse gave a small shudder, then everything OK. Now reverse slips and goes very slowly. Forward gears seem just fine, so far. Fluid level is at correct level on the dipstick. I drained and filled the AT fluid 5500 miles ago and all was well. Filled it with Valvoline MaxLife synthetic. Will another drain and fill be worth it? Or should I take it in to the shop? Is this the beginning of the end for this transmission? Thanks.