Sir Bowl,
I agree with the previous suggestions.
I might add that timing, in addition to your grip, can also be at fault. The stance is critical to a bowler's approach. Be sure that at the stance you are completely relaxed, and that your feet and pushaway are properly synchronized during your first step (if 4 step, else on 2nd step if 5 steps); walk normal to the line (don't do anything fancy with your hand while walking -- the ball is merely being transported at this time), and upon your slide step, feel the ball coming down on the downswing (wait), and prior to the ball reaching your ankle, just let 'er rip through your target AND stay down.
Regards,
BowlingWolf