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Rpms skyrocket & car slows down while in drive

Its a 96 Subaru Legacy. Had it for over a year but is not driven often. Soon after it started being driven regularly the rpms would randomly skyrocket, nearly to engine blowing level & would slow down like it was in neutral. The speed it’s being driven at when this occurs doesn’t seem to matter. If you put it in neutral & then back in drive sometimes it’ll correct itself. Other times you have to completely shut the car off then start it again. Thoughts? I need it fixed soon.

Check the fluid level in your transmission. If it is low, put in only the absolutely correct fluid.

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Yup, and pray that the tranny hasn’t fried itself already.
Whenever an engine revs and the car correspondingly slows, it’s because the drivetrain components that connect the engine to the wheels are no longer firmly connected. In an automatic transmission, it means the torque converter (a fluid coupling device) is no longer effectively transferring torque to the transmission OR that the innards of the transmission are no longer effectively transferring the torque to the tranny output shaft. Generally that means parts are slipping and that manifests itself as fried components.

Follow the instructions in your owner’s manual for checking your transmission fluid, make sure it’s at the proper level, and hope… and don’t be surprised if it’s black and smells burned. If this helps, drive it to a reputable tranny shop (NOT AAMCO or any other chain shop) and have the tranny flushed and refilled. If it doesn’t, you may be looking at a very expensive repair. A tranny shop can advise you.

Excellent advice above. fyi, Automatic transmissions have clutches just like manual transmissions, just more of them; and the symptom you are describing is usually that one of the clutches is slipping. There’s a pump inside the transmission that pressurizes tranny fluid and that pushes on the clutch. So either it isn’t pressing the clutch w/enough force, or the clutch part is just plum worn out. A proper service can sometimes return the fluid pressure to spec, and that fixes the symptom. that’s your best bet. If that doesn’t do the job, and you’ve been living a good life, it’s possible there’s an electro-mechanical actuator (solenoid) that has failed. Often this problem means the clutches are worn out, which means a transmission rebuild. A good tranny shop will usually want to measure the pump output pressure before deciding on any diagnosis. Best of luck.

Shot in the dark. I would have the pan removed and have you oil screen inspected. Could be that while your driving and the fluid has some debris in it and starts to plug up your screen. When you come to a stop, engine slows down and the screen doesn’t have to pass so much fluid so the debris settles to the bottom of the pan again. Same happens when you turn the engine off. After driving again, same o same o. If so, you might be in need of a reman unit.

I’m thinkin’ George is (incorporated into his comment) suggesting the torque converter lockup clutch, which I forgot about, is failing. I think it’s a good point.