Howdy everybody,

I'm not a mechanical whiz by any means and I hope I'm not asking a question that's been asked a billion times (although this probably has) but I my 2003 RWD v6 Blazer is idling roughly around 500 RPMs when I start up. I started having problems about 3 weeks ago when I pulled up to a stop light and the engine cut out on me. It started back up and stalled out on me 2 more times before reaching the parking lot. After suggestions from everyone I have:

-Used fuel cleaner
-Changed the Air Filter
-Changed the fuel filter
-Sprayed and cleaned the IAC and Throttle body
-Inspected the air intake hose

The SUV didn't change in the slightest. I noticed that the previous mechanic had left 1 out of the 4 screws cocked sideways during instillation of the Air Filter Housing which left a quarter inch opening which I resolved when I installed the new filter. It so far has not cut out on me while driving but it'll die some days at start up where it jump to 500 RPMs and fluctuate between 400 and 600 before dying. I have to give it some gas to keep it running on days like this.

I tried something a little different in that I disconnected some of the sensors to troubleshoot. I started with the MAF and nothing changed. I disconnected the Intake Air Temperature Sensor which resulted in my blazer surging to 1000 RPMs at start up then slowly dropping back down to ~550 RPMs (jumps to ~600+ when in park) I changed the IAT sensor thinking that might be the problem and now my blazer surges to a 1000 RPMs and drops back to 550... most of the time. A couple times so far it's started up at 500 and fluctuates between 400 and 600 as if it's going to die on me like before but it catches itself.

I tried bringing it to a different mechanic on base and he said that it might be the ECM because it's not kicking off any fault lights. No SES no nothing. The SES and the fault lights come on at start up but then go out as expected. Is there anyone that might have a clue as to what the problem might be?

Another quick question is identifying exactly what the vacuum hoses are because I've been meaning to inspect them and I might sound dumb but I'm not certain which ones they are.