2001 deville missing
 

Hi i have a 2001 deville 8th dig in vin is "y" my problem is that shortly after start up the car will start to develope a miss.it will get to point where its missing bad scanner shows cyls #8,6 and 4 missing 8 being the wost.then it like just smooths out again and in several secs starts all over again. It will do this at idle or while driving. Ive checked coil pack even swapped from one bank to other .checked plugs pulled injectors and had checked. Did a compression test.even when its running like crap theres still spark at plugs. But you can smell the unburned fuel.dose anybody know what all the sensors should be reading at idle on a normal running engine. O2 sensors,map,iac,trim,ect. Ect. Oh one other thing i did notice is that when it dose do this the loop status changes from open to closed. Any help would be great. Thanks.