Okay, check this out....I just installed a new IMC & started the car. It idled pretty evenly for the first 1 1/2 mins then the engine started "lurching" again. It'* a misfire of some sort. I've replaced the spark plugs, CoilPack, IMC....still the engine just wants to konk out. Now...before you start sending back what you suppose the problems are, here'* a little more information. Earlier today I put on a new Neihoff IMC & started the car....it idled immaculate. When I decided to take it for a drive, there wasn't any compression, I floored the pedal & the car was barely making it to 60 kmh. I popped the hood, looked at the IMC/CoilPack again & one of the connections broke off the CoilPack. I brought the CoilPack back to the local parts distributor & exchanged it for a new one. Now...when I put the NEW coilpack back on the idle problem returned. So..what the sam-he$$ is up with that?
I guess my problem is this...to put it another way so everybody can understand it....When I start my engine the part that looks after engine idle for the first minute or so does just fine...but THEN the engine shifts over to the Idler or something & that'* when the engine just starts hugga-chuggin' Has anyone replaced the idler before on a 90 Bonneville LE...is it easy, recommended? I ask because when I popped the hood to watch the engine as it coughs, what I thought was this loud knocking sound from inside the engine actually turned out to be the Idler colliding with the engine wall.
Your answers & suggestions are greatly appreciated.

Sounds about the time between open loop operation and closed loop. Suspect it is time for a full set of scan tool readings, something is wrong but might be an obscure sensor.