Z28 doesnt run very good??

This is a 89 z28 with a 5.7 I put in new wires and plugs cap and rotor. Also a new icm and tps I also replaced the throttle body gasket as it was falling apart. My problem started with the vats and thanks to this site i got that fixed(thanks for making that a pretty easy job) Now my problem is that the car stumbles and smokes (black rich) at idle and no power when throttling up. I did once get a maf code with this car also but once i adjusted the tps i didnt get it anymore. Now intermetantly while driving i get the service light to come on!!! But the car seems to run better when the light comes on more power but seems to idle high?// Could the iac do this i wouldnt think that it would effect when throttling up. Thanks again for your help in the past and any help in the future.

There should be a code stored from when the light came on when you were driving, pull the code.

Pull the code..if it is a 33, replace the MAF power and burn off relays.

by burn off and power you mean the unit mounted on the intake tube by air filters?

by burn off and power you mean the unit mounted on the intake tube by air filters?
No. There are 3 relays on the firewall by the brake booster. They are; MAF power, MAF burn off and fuel pump. Replace the burn off and power relays, they cost about $15 at autozone or the like.

Morley, what's the function of the burn off relay?

Morley, what's the function of the burn off relay?
As you drive the heated wire of the MAF can get road grime built up on it and degrade the sensor's ability to read correctly. So, when yoiu shut down the engine the ECM energizes the burnoff relay and sends 12v across the MAF's sensing wire, heating it up red hot to burn off any "crud" that may have accumulated on it.
GM has always reccomended that if you have to replace one of the MAF relays, that you should replace both.

Turned out to be the main computer. Got new one installed and now run like a champ!!!! Thanks this is one cool site