Starter on 1995 chevy blazer

How can that be? What do you mean sticking...

Starter keeps cranking when n park but quits when put n drive

When I try to start it the starter doesn't turn over it just keeps cranking trying to start

So the motor does not turn over because of the starter? Or does the engine turn over but will not start?

Oh, the starter keeps running, turning the engine over, right?

It will start and run but the starter will not stop running to u pot in drive

What's

Sounds like the ignition switch is sticking, making contact in the start position. or the starter solenoid contact is sticking. One or the other. You could tell if it is the starter solenoid by testing on the small wire running to it with a test light, if the power stops... when the key is released from the start position, there should be no power there and would either shut off or keep turning, indicating the starter solenoid if it keeps running. If the power still stays on when the key is released from the start position, then it would be the ignition switch.