I have a 1995 4runner with a 3.0 V6. I purchased it with blown head gaskets and and changed out the gaskets, got the motor back together, lined up all timing marks, put timing belt on. Spun motor over by hand to check marks only got half a turn on the crank and timing belt already started wanting to walk off front of tensioner pulley. Replaced tensioner pulley, still have same issue, checked to see if cam pulleys are lined correctly with each other and they are. Any suggestions to solve this??

 

Have you looked in the FSM to ensure the cam pulleys are on correctly? Timing belt guide correctly positioned?

http://www.ncttora.com/fsm/1993/engine/67timingbe.pdf