89 cherokee multiple engine problems

this cherokee has been beat into the ground many times and am looking to fix it up a bit. numerous problems have popped up one after the other, and have been fixed. this one is a mystery still. in park rpm will not exceed 3k. in drive no more than 2k, and because it won't go over 2k in drive... it won't shift. i've been told many things that it could be but all of them are expensive and would like a more exact answer. i've heard it could be the egr valve or selonoid, computer, or fuel pump. can anyone help me??

well buddy it sounds like it could be the throtell position sensor wich costs 160 canadian. my truck is an 89 and that was my trouble with the tranny. try to see if you can get it checked to see if it is working or try unpluging it and see if that makes a difference. if there is no change than thats your solution. but still see if you can get it professionaly checked