When im on the highway doing about 50-65 my Blazer pulls a little to the left when i press the brakes. I know that the idler arm is shot, can that be why? The steering has a lot of slop, and I just had my brakes done. New pads, rotors, and calipers all around.

 

then your right caliper is not working. when you stop and only one brake works the side that cant stop will continue forward...so if you brake and pull left then check the right side.
most likely your pads are binding up and not engaging fully.

 

Mine's been doing that recently. I thought one of the front calipers was hanging. Had it in to the mechanic and he said the front brakes were fine, but the cylinder on one of the rear wheels wasn't releasing. Gonna start a thread on that because I've got a question that needs answered and don't want to hijack this thread...

 

If you just had your brakes done the mechanic could of not lubed the slide pins corectly on the calipers and one will not slide. If you know the steering is worn out that could also definitely be the problem only thing is it would also wonder around a bit if that stuff was also worn out

 

This is most likely a binding R. brake, as they've said. Maybe the junkyard will have an idler arm so you can replace that for cheap.