98 Blazer, Tranny problems or something else

[aleekat]

98 Blazer SUV, 4x4. Hope someone can help troubleshoot.
Automatic, 4speed. Only occurs when RMPs are below 2000. It seems that when the tranny downshifts, rpms start going up/down, between 1100 & 1800.(mainly going uphill) And you can feel it. Can't duplicate it in 1,2,3. If I give it gas, or let off the ossilating goes away. Only 112k, fluid it good. None of the 4x4 lights flicker. The 4x4 system works as advertised. No check eng lights, etc. Has no codes stored(if the guy did it right)
Any tips, suggestions etc welcome.

[MT-2500]

Originally Posted by aleekat

98 Blazer SUV, 4x4. Hope someone can help troubleshoot.
Automatic, 4speed. Only occurs when RMPs are below 2000. It seems that when the tranny downshifts, rpms start going up/down, between 1100 & 1800.(mainly going uphill) And you can feel it. Can't duplicate it in 1,2,3. If I give it gas, or let off the ossilating goes away. Only 112k, fluid it good. None of the 4x4 lights flicker. The 4x4 system works as advertised. No check eng lights, etc. Has no codes stored(if the guy did it right)
Any tips, suggestions etc welcome.

Engine running or transmission problem either one.
I would find a good repair shop with a good transmission/engine capable scanner and have it checked out real good..
Make sure engine running is up to par.
How is the tune up and has transmission ever been serviced.
Fluid level and condition good?
A engine has to be running good for the transmission to work good.
Watch tps sensor for drop outs and check fuel pressure check to.
Good luck and let us know how it goes.
MT