99 Blazer LT 4.3 L V6 idling rough and stuttering on acceleration from idle
 

I need an assist here, first post so I apologize if it's rough. Here's what's up so far. My starter fried. I mean FRIED, it shorted out and blew a cloud of smoke out. When I pulled it to replace it the plastic on the solenoid was burnt and crumbling. I got the starter taken care of, fired it up and it starts with zero issues. The problem that came up after this was that now it idles rough. It sits at 600, then revs to 700, then drops to 500. It does this in idle only, and if you keep it above that 700 RPM mark it runs like usual. If you do have to stop and it does it's weird idle, when you hit the gas it stutters, lags, and takes forever to catch power until it's above that 700 RPM mark. I have some competing theories here. First is a vacuum leak. Second is a bad fuel filter and third is an O2 sensor. I'm leaning towards the O2 sensor but the vacuum system does have a leak, I'm just not sure it would cause these issues. The fuel filter probably needs to be changed but it doesn't make sense that it has perfect performance other than at idle and take off to me. I've asked around quite a bit to mechanics (I know enough to be dangerous but I'm far from a trained professional) and I'm trying to gather some more opinions on what on earth could be causing this. Any input would be really helpful!

If you know it has a vacuum leak start there abs just replace all the hoses. Pretty simple and costs around $20. Then just replace the fuel filter while you're at it for another $7 or so bucks. If that doesn't solve the issue I would clean the Egr valve not hard to do and only a couple of bucks for cleaner (there is a write up in the tech section here or you cab Youtube it). That should take care of your issues unless you have an CEL code and that would lead to your problem.