5hp18 on BMW 530i slips

Hello everybody!
I have 1994 BMW 530i with 5spd 5hp18 autotranny. It slips in first 1-2 and i believe 3 gears but drives good in 4 and 5. I just drove it for 400 miles on the highway. It slips really bad when takes off. I have to push accelerator really really weak untill i gain 30-40 mph and when higher gear will kick in and its fine. I couln't find any information regarding testing 5hp18. I want to test wiring harness, sensors and solenoids also perform pressure test before ordering rebuilt kit ($546 dollars).
Where i can find this information? I looked through Mitchell Transmission Service and Repair book. It doesn't say nothing about 5hp18
sincerely,
Akmal

have you changed the fluid and filter? if it was never changed it could be partially clogged and driving it like that will smoke the clutches resulting in either a replacement or complete rebuild.

When I bought the car the owner told me car has tranny problem. He changed filter and fluid. I looked at clutch and band application chart it seems more like electrical problem.