wierd idle

my idle is at a little under the 750 mark when i start and drops to just above the first line(500 i assume) after it warms up, this seems a little low and i was wondering if there is a way to change it?

its a renix 4.0 in an 89 limited. its also got an aw4 and 242

We need a little more info like what year and what engine.

sounds like a dirty idle air controller. Have your throttle body cleaned and that whould fix it. It should be removed from the intake and made sure the idle ain controller passages are clean of gunk.

I have the dealer tech do mine, it 1 hour labor and he hooks it up to the test set and make sure it all running well.

When you go in tell the service writer you have a fluctuating idle and let the tech figure it out. let him earn his money.