98 Chevy S-10 Idle Speed Problem

I have a 98 Chevy S10, 177,000 miles, 2.2L 4-cyl. A few days ago it started idling at full throttle. It would drive OK in gear, but it idled at full speed.

The check engine light came on, and I have 2 error codes:

P0336-- Crankshaft Position Sensor A Circuit Range/Performance

P0507--Idle Control System RPM Higher Than Expected

I found a busted vacuum hose and replaced it. Now the engine lopes excessively at idle, but doesn't race like before. Any hints at this point would be greatly appreciated.