I just bought a 94 Blazer Tahoe LT and it ran fine up until about a week and a half ago when the idle started running ruff and now it surges when I let off of the gas and I sometimes lose brake pressure as well which I understand is linked to the intake system. Any help figuring out what I need to fix or replace would be awesome.

 

Look at the egr before you spend any money. Sometimes just a thorough cleaning can work wonders

 

ya could be a lot of stuff causing the rough idle. the easiest ways r to one look at ur spark plugs and see what they look like and two check/clean ur egr valve.