i recently bought a 97 e420 (month or so ago) with 150k miles on it, and i initially noticed no problems. few days ago on a cold morning (27F) the car started normally i took a short trip and on my way back the transmission got stuck on third gear and would not upshift no mattet how much i revved it. I tried to manually shift the car or put it on N and back on D. it did go to neutral but when back on D it stayed on third gear. i stopped the car, turned off the ignition and turned it back on and it shifted fine. well if that wasn't weird enough, the next morning (just as cold) i drove the car and i noticed that the shift knob was hard to shift between D and 4, before it needed only a simple nudge. then after about 30 minuted of driving it would become significantly easier to move. the transmission was shifting fine at all gears though. i remenberd that that had happened the day before too. also on that same day when trying to back up the knob got stuck and it would not engage in reverse (it would move to the reverse position or park but would not engage). the car was still engaged in drive. then i forced the knob back to drive and i heard a pop originating from the top of the trans (no internally i think). from then on i could shift the trans in all positions and it engaged normally. So here is my delema! WHAT THE HECK IS HAPPENING TO MY CAR! i drove the car this morning and it drove fine, temperatures where in the high 40's. I'am speculating the the AT fluid is in desperate need to be changed. i don't have the updated service records for the car, so i don't know if the trans has been serviced before. any ideas! your help is greatly appreciated .