1999 Nissan Maxima Auromatic Transmission 4th gear electronic overdrive intermittantly slips.

179,000 miles. 3 speed auto with 4th gear electronic overdrive. If overdrive is not employed all shifts fine. Had all the electronics checked out inn real time as we drove down the road. No faults recorded. However, if overdrive "IS" engaged at a start (traffic light) the car may or may not hook up. When it connects at about 2K rpm you may get a nice smack in the back of the head as the transmission connects to the engine and the car launches forward. Continuing on in overdrive mode, it's mushy through 2nd and 3rd until it finally finds the 4th gear overdrive and then intermittently slips. It does not drop back into 3rd but does intermittent slipping in 4th gear (overdrive) Did an experiment on the freeway, overdrive employed. It pulled nice and tight through thru the 1st 3 gears then hooked up fourth No Prob. I set automatic cruise control to 2500 RPM (about 71 MPH) Was surprise to see -0- fluctuation in either RPM or speed. Pulled the stick the color was "not pink" but was not brown or black either. I smelled the fluid and it smelled a little burned. Wiped the dipstick on a white shop cloth.. color was dark but did not notice any obvious clutch shavings I think I need a clue. I'm looking for an alternate solution to R n R'ing the transmission. A rebuild costs more than the car! Other than the obvious bone yard remove rebuild and replace, have any thoughts on things I haven't covered or a suggestion to alternatives to making the $2000 Plunge into R&RR . Any help would be appreciated. Thanks heaps for the read.