Major loss of power on hills

[puty72]

1989 ranger 2.9 auto 4x4. 121,000 miles . I am having problems with my truck with major loss of power going up hills it won't even kick down in just makes a loud deep exhaust note with the Rpms up around 4k . It just started doing this a week ago

 

[adsm08]

If the engine is turning 4K it sounds to me like it did kick down (other wise known as down shifting). Is it possible the trans is slipping rather than a loss of engine power?

 

[RonD]

Yes, 4,000rpms would be about 90mph in 3rd gear, assuming 4 speed A4LD.

If it was a sudden loss I would check exhaust for blockage, muffler or Cat could have collapsed inside restricting exhaust flow.

 

[softshellcrab]

I just got over the same issues with my 90 2.9 and it was timing. Although your's doesn't sound that easy.