New to this 95 lt1 24x help

I finally got HPtuners working had some issues but I scanned the car tonight and I have a bunch of codes that read MIL on second error. Codes from the TPS MAF coils injectors coolant sensors (which quit working randomly) and others. I looked all the codes up and they all say it could be a power or ground issue. Do they all have a common ground somewhere? The MAF TPS and temp sensors are all brand new and the harness is brand new from the 24x kit. Any input would be appreciated and if it's computer related try to dumb it down some I'm totally new with the software and all. Car will start and cut right off I can get it running if I give it throttle it won't idle unless I drive it and get it warmed up it runs real rough until it's warm it has a mail tune I had done to get it running