1995 850 NA/ 180,000 miles.
I have mentioned this before, but it is getting to be an increasingly annoying problem: As I accelerate...parkway speeds...light acceleration...the rpms rise and then drop about 200 rpms. It would be akin to the car shifting gears, when it reaches max, it shifts, thus lowering rpms...EXCEPT, there is no shift change. Light acceleration, rpms rise, then drop about 200-300 rpms... I changed the tranny fluid...this didn't do anything. I know very little about the technical end of things, but I would love to think it's a vaccuum hose of some kind rather than slipping gears. The car NEVER slips out of gear, either up or down. Shifts nicely...

 

Is there an up arrow showing up on the dash board. Have you checked the transmission computer for codes. You can do it yourself being your car is a 95.

 

No up arrow. I will check the diagnostic thing this weekend.

 

Mine was doing that for a while. I replaced the PCV and found that 1 of my vacuum hoses was coming loose. One at the back side of the PCV hose. My guess would be a vacuum line somewhere.