Does anyone have a clue as to why my 1991 Ranger 2.3 manual five (5) speed transmission losses acceleration after engine warms up when in 5th gear. Most noticable when climbing hills. In addition, the Check Engine Light comes on well. I have tried to decode the check engine light as well but it goes out after turning the ignition off. I have removed the catalytic converter but still the problem persist.

 

I finally got my codes for my engine check light which was a 33 which point to the EGR Valve or EGR Position sensor. I replace the valve and this seems to have solved my problem with the engine check light but still losses acceleration while in 5th gear during highway driving.