My lawn mower is doing the same as the other guy. Runs fine when cranked but as soon as I pull the knob to engage the blades, it slows down the motor and then goes dead. My blades spin free and my belt is clear of grass. What could this be?

If it is a riding mower and has a new belt(s), the belt is probably adjusted too tight. I had the same problem after installing a new belt.

If it is a riding mower and has a new belt(s), the belt is probably not adjusted correctly. I had the same problem after I installed a new belt.