Took off MAP sensor wire

I have an idle problem on my 92 suburban.It starts out on cold at 1100 rpm,after a few minutes it drops to 700 and starts to dip lower and come back to 700.It goes on like that forever.
I pulled the map wires off and it sounded so quite and was steady at 500 rpm,but the check engine light came on.What is associated with the map sensor being removed?What other sensor would effect my idle like that.
I just checked my tbs sensor for resistance and changed my stuck iac valve.I'm going to have that map sensor checked.I don't drive this truck so it's hard to get the codes.I need it scaned.:runaround::screwy::confused::banghead: :nono:

What size engine, and is it TBI injected.?

The MAP sensor helps the PCM determine engine load %.

When you replaced the IAC valve did you clean the ports ?

Also test the Engine Coolant Temperature sensor.

It's a 5.7L.TBI injected.I cleaned inside of ports from both sides on IAC port.I'm going to check the coolant temperature sensor.I blow into the line that leads to the fuel vapor canister in it was leaking.Do it suppose to hold pressure?

The MAP sensor is vital to engine operation. The fact that it idles without one doesn't mean it will work in any other range.

Have you considered that it might be the MAP sensor failing?

I'm going too have it tested tomorrow.