OK here is the truck

98 12valve 215000 miles
hybrid 35/40 turbo
some pump work

I just had a new clutch put in from southbend. Before I took it to the mechanic it was running great, except for needing a new clutch. after I get it back it now boosts decent but it feels like I'm towing someting extra heavy when it's just a little horse trailer. poor power and the exhaust temps shoot up to 1200 real quick and feels like I'm driving an oversized 4 banger with little to no power.

checked trans fluid- good
turbo- good
brakes are good
both differentials have fluid.

What could be wrong with this? Please help I have no idea what to do and it is running not even as close to as good as it was a week ago with a bad clutch