Help troubleshooting deck issue

I picked up a non running LX255 and now have it running great. I mowed with it briefly and the deck was in good condition just very dirty and the blades and deck belt were worn. I installed new blades, the "cups" / spindle guards and a new deck drive belt (Stens Part # 265-242) and inspected the deck spindle belt and put it back on. I removed the spindles and cleaned them and inspected them and put them back on. I removed the deck belt pulley and cleaned it and inspected the two bearings and put it back on. The deck went back on smoothly. I started the mower and when I engaged the PTO the engine bogged down and died. I restarted it and was able to turn the PTO on/off/on/off and then on to start the blades turning before fully engaging it. The PTO then engaged and stayed running. After a few minutes I disengaged the PTO and then it did engage with one pull of the switch but I could tell it was struggling. When the PTO is engaged it significantly reduces the overall engine power. Did I do something wrong? I first thought is that the new deck drive belt is too tight, if so, what deck adjustment would I make to relieve the tension? What else could cause this?