Hi, I have an 84 528e that has about 260,000 miles on the original transmission (ZF 4hp22). My problem is that when it hits around 52 mph, it doesn't shift into final gear right. When shifting properly, it should go from around 2000-2100 rpm, down to around 1500 rpm. Instead, it goes from around 1850 rpm to around 1700 rpm. When driving around 65 mph and I let go of the gas pedal, the rpm drops a bit. Before, it slowly dropped and remained a steady drop. I've searched the internet but have not been able to find much info on this tranny for this particular model. I believe that the culprit is that the torque converter isn't locking up. I first noticed a pattern when it would rain or have been moist the night before, it would act up. It's been getting more frequent lately. Even letting the car warm up for 15 minutes didn't solve it. I'm not sure what the problem is. Is it electrical or mechanical? My big question is does this tranny have an overdrive relay, and if so, where can i find it? Any suggestions about what could be causing this problem would be appreciated. Thanks