Jeep Repair: cherokee intermittent starting and tranny probs, cherokee, gears

Question
I've got another question about my '97 cherokee with 138k mi.
Occasionally it won't start when it's in park...it won't even turn over - nothing. I move it to neutral and it starts fine. I've heard this might be some sort of safety sensor and if i clean it, it can fix the problem. If this is true, where is that sensor and how would i take it out/clean it?

Also once in a while, i'll pull up to a stop light and my tranny will feel like it's still in 4th gear - like it's not down shifting and the check engine like will come on for a while. If i manually shift into lower gears, they work just fine. what could this be? Is there anything i can do to fix it myself?

thanks again!

Answer
I am not sure if it will effect the shifting but sounds like to me your neutral safety is the starting problem.  When they stop working you can start the vehicle in neutral or jiggle the lever and it starts.  Most of them I have seen have to be replaced, they can't be fixed or cleaned.  I would get that Engine Light checked out by a technician.  Hope I could help you!