New IAC, now check engine light comes on

I put a new IAC in last week, and when I put the car in park, the check engine light came on.
Went to autozone, and they pulled the code. High idle. said to check the IAC. Told them I bought the unit from Autozone.
I've checked the connections, cleaned out the port on the throttle body where IAC goes into, and all is good there.
I'm thinking of putting old unit back in, and taking new one back claiming its defective.

What do you guys think???

Thanks!
Paul

this may not help, but I will make a comment. A couple of years ago I bought an IAC for my son's 94 Beretta from Autozone. Put it in and ran terrible. high idle, not like it should. Took an old one out of a parked Corsica (91) and put it in and no problems. I think on these sometimes it is better to buy a higher priced unit, say from NAPA, Advance, or even from a dealer. the Autozone one had what looked to be a very weak design. May try the old one again to see what happens. Note: I know Advance offered at least 4-5 different ones, but stocked the cheap one, same as Autozone. but they could get me the better one in 1-2 days. As it was, I left it alone. there could be more to this, as some sensors can cause a code in another sensor. but I would try this for sure. Be sure your intake assy (rubber hoses to air filter) are not cracked, leaking, etc.

I purchased an IAC from Autozone for my TBI Chevy truck. It is the same design that is in your vehicle.

After a week the "pintle" detached from the shaft and sucked up against the port which shut the engine down at idle. They are lucky that it isn't able to enter the engine from there.

That was the last time I purchased parts from them. If you plan on keeping the vehicle OR want it to be reliable then you should purchase parts like this from the dealer. Engine control sensors and controls are to critical to not buy them from GM.

Take Care and hope all is well at this point.