Isuzu: Isuzu Rodeo low idle, isuzu rodeo, compression test

Question
Hello Derek
 I recently purchased a well maintained 93 Isuzu Rodeo
Around 90k, speedO not working. Starts and runs well but after warming up 5 min or so when coming to a stop the idle drops to 7500 or so almost stalls and does when shifting into neutral; oil pressure drops to about 0 with idiot light flickering. tried adj. throttle but no good.
Also check engin light comes on after 20min + -
Any help greatly appreciated  

Answer
Hi there,
I hate to say it but it sounds like it is losing compression. The motor sounds like it needs to be rebuilt. Take it to a mechanic you know won't screw you and have him run a compression test. That is what my motor did when I had to have it rebuilt. if not that, I don't know what else.
thanks,
Derek