I wouldn't signoff on a terminal condition without double checking.
Option 1: DIY, take out all the plugs, turn crankshaft by hand wrench while making sure the camshaft is turning (maybe remove the valve cover), This should require less than 20 ftlb of torque.
Remove belts to be sure it isn`t the PS pump, A/C compressor or even a bad pully.
Look for and eliminate any other external drag/friction that could cause this. Consider that a bad pully or other hangup on the serpentine and/or timing belt belt could cause this.
Option 2: Take it to a shop that specializes in engine repair and let them diagnose it. If it's a good shop, they will quickly get to the real cause.