IAC = Idle Air Control, you can read all about it in the "Tech Info" thread atop this forums thread listing page.
A search will turn up all kinds of threads on troubleshooting, cleaning, or replacing the IAC & doing a fuel pressure check.
If your going to begin turning wrenches on your ride, it would be a good idea to consider purchasing a repair manual, CD, or factory repair manual, or if you don't want to purchase something, drop by your local library for a manual, to familiarize yourself with what & where things are on your particular vehicle & how to properly & safely work on it.
We can offer up suggestions on particular things to do & specific things to look for on a trouble shoot, but we have to depend on reliable feedback input, to make good guesses.
Most autoparts stores have a fuel pressure gauge in their "Loan-A-Tool" program, for a refundable deposit.