95 buick riviera hard to start hard to keep running

Hi guys and gals;) I just replaced the supercharger on my 95 riviera and I am getting a really rough idle if it wants to stay running at all. I can keep it ruining if I stay on the gas but it has a real problem getting up past rough idle and is rough all the way through to 3500 after a while of holding it around 3000 or so it smooths out but still seems to have a bit of a miss and I have a check engine light that comes on after a little bit of running then it starts running rougher almost immediately Also may be unrelated but i the higher the rpms climb the fuel gauge reads less and less gas (haha I know thats what happens) and then if the rpms drop it starts reading more gas.

Why was the SC replaced? Bearing problem?

Was the rough idle there before replacement?

Sure sounds like a possible vac leak.....

I replaced it because my old one was making a really annoying noise at idle and I thought the bearings were bad but then found out about the couplers in them go bad really often so I replaced that too.
There was not an idle problem before but it would throw the same check engine light and trac off light and it would make the car run rougher as soon a they popped up then if I shut the car off it would start back up and no lights or codes recorded in history.
Im going to check for vac leaks tomorrow but I think the engine light is still going to be there any ideas on that.
Thanks so much for any help

If it started to run rough when the CE light came on, what are/were the codes? If that CE ight comes on, there has to be a code in history.....

There is a vacuum/boost line in the LIM, which is located below the S/C snout and goes to the MAP sensor. Are you sure that is connected?