Rep Power: 0

I have a 89 irocz 5.7TPI and when i first start her up it has a nice steady idle afer about 20 minutes the idle gets low and kinda jumps up and down at a stop and the oil pressure gets really low as well. I dont know what the problem is?

 
Rep Power: 1069

idle air control, ignition module, and a few other things can do that, start with a full tune up, and clean the idle air control and maf sensor (I think the '89 had mass air flow)

 
Rep Power: 602

Check electrical section

 
Rep Power: 0

Thanks for the suggestions. and i did just about everything, changed the IAC sensor,then check ignition module, did a tune up, changed the wires, changed the mass air sensor, and it still idled like that. But what i just did this weekend changed everything. I changed the old injectors, ERG valve, and the fuel regulator. I put rebuilt Bosch injectors n a new EGR valve, n a ajustable fuel regulator. That did the trick..idles n runs like a million bucks!!!!!!