Crank sensor problems

Perfikt

Ok, so, I've been having a problem with my used 2010 since day two (see here for the old thread...)

Short version: car had check engine, vdc, and slip lights on when headed to work, wouldn't start at all on lunch, towed to mechanic (not a dealer, but mechanic we have used before) and they ended up changing crank position sensor. Car started, but once it warmed up and they tried to start it again, no dice. They unplugged the crank sensor, it starts on 2nd try. (every time) Mechanic said a car isn't supposed to even start if that sensor is unplugged... But that is the only way the car runs, and even then,, it stays in limp mode and won't get above 3200-3500 rpm.

I need some help on what to try to do to fix it at this point, or what may be causing this. The mechanic suggested either the computer tune is bad, or the actual computer itself.