Stange problems on my 93 WRX

Performance is fine, but the bottom pulley, i think its the crankshaft pulley,the pulley in front of the timing marks, is shuddering quite bad.

When the car is idling and you turn the steering, the belt is slipping something rotton, and you can feel it shuddering when the car is picking up from idle speed, like i said performance is still fine. Took car off the road and im not using it till i find out whats up and i'm humbly driving my tigra, so obviously i need help asap!

 

Remove the pulley bolt, check the pulley key hole that it isn't damaged then loctite the bolt and tighten back up, sorry can't remember the torque.