The very first thing to check is the bushing inside the rack on the passenger side. While someone is closely watching the steering rod to see if the rod moves upward before turning the wheels, a second person turns the steering wheel. If the rod does go up, the bushing is shot and must be replaced. Don't bother with a stock bushing- they are plastic and wear out before your eyes.... all the Pantera vendors sell a bronze substitute which works better, longer and is simple to install.
If its not the bushing, I'd look to see what the wheel alignment was; Panteras work well with 1/16-1/8 toe in, as much caster as one can get (about 2-1/2 degrees) and 1/2 degree inward-at-the-top camber. This also works at the rear except that caster is not adjustable. Any shop that aligns Corvettes can fix your Pantera.