98 Cherokee XJ

I have a '98 XJ and just recently it has been stalling as soon I start her. I literally have to give her gas to keep her alive but once I shift into R or D she's fine, no stalling. I cleaned the throttle body last night, replaced the Idle Air Control Valve sensor and throttle position sensor. I cannot figure out what the problem is. I've ruled out the fuel filter just because she's able to run after I get her in Reverse and Drive. My next guess is the Crankshaft Position sensor. Any thoughts...... Anybody..........