idle problems on a 99 rodeo
 

Recently a shop replaced the idle motor on my rodeo and the engine went back to running as normal. Now, about a month later the engine is once again idling at 2400 RPM, and when I put it in gear it wants to light the tires up and feels like it is trying to rip my transmission from the rodeo.
If I just had it replaced, does it need adjusting, and if so how do I do this?