Can You Help? 1990 Jeep Cherokee,won't Shift Into Overdrive, I Replaced Tps And Still Nothing. With Old Tps Trans Worked Fine But Was Hard To Start,and Sometimes Would Not Start At All, And I Think It's Using More Gas. Please Help Crappy Jeep Owner.

I have the same problem. Its your neutral safety switch. Two parts. One is cheap $40 and one is expensive $300. Most likely its the more expensive of the two. If your rear drive lights don't come on that could be the problem. If your check engine light is on that could be the problem. If your car wont start some times  and you need to put it in neutral and back to park then that could be the reason. If this is not the reason, then you may have a bad sensor somewhere or some air flow blockage.

Calibrate the new types