99 Explorer Trans "D" issue

Hi all, I'm usually over at the LS forum dealing with that cars demons...now I'm needing help on my 99 Limited. SUV is a 99 Limited, 5R55E with 170K...I've owned the car since 45K and within the past 6 months the tranny needs RPMs up before it will kick into drive and move forward...reverse, shifts etc all fine just slips/surges before engaging into drive....mostly when coming out of park to drive but it will do it from time to time when stiting at a light and going fwd in drive. I dropped the pan and there was minimal if any debris in old fluid/pan (actually looked good for 170K) changed fluid/filter and it performed well for about 3 days...then back to it's old ways...I just dropped pan and put the upgraded bracket on the EPC solenoid (really nothing wrong with old one after pulling it off) and torqued down the valve body within spoec and it still does it...started out not as bad but after a few miles right back again. I'm thinking of changeing out the EPC solenoid and maybe a new Valve body gasket,,,any thoughts...A garage is OUT of THE Question! I do all my own work and basically trust no garage within 100 miles of me (and further) o/d light did flash once for about 10 miles during the past 6 months but hasen't done it for some time.