Issues Downshifting when climbing hills

[Toyota4runner4life]

My 1997 4runner is having a issue when i am attempting to maintain highway speeds (50-65mph) while going up hill. I'll be going down the highway around 60mph when i come up on a hill. as i hit the hill my rpm's and speed will begging to drop and then the trany will attempt to down shift to maintain speed, but it starts to slip, causing it to jerk and not shift out of high gear. I have chained and filled the with little help. when this happens the check engine light comes on and blinks until i let off the gas, and back off the engine.

 

[shootmymime]

Sounds like a motor problem. Surprisingly a malfunction engine can simulate a slipping or weak transmission. Bit in reality the engine it not able to produce enough power.

But I could be wrong.
Go get the codes scanned and report back. They should still be stored even tho there is no current cel.

Good luck