My apologies ahead of time if this has been discussed but I haven't come across similar issues. Jeep was running fine until battery died and ended up installing new alt/battery. Now having some issues. I will start with my wife stating fuel mileage is a lot better since new install.Well that tells me its now running lean....but no check engine light.So I grab the keys to go for a drive...yep...no check engine light but I notice at start up when the fan clutch engages a noticeable RPM drop and when it shuts off back to the norm. So I go for a coffee run and everything is good but when I'm waiting in drive-thru line it sounds like it wants to stall.On my way back home it did stall on me when I came to a complete stop.Starts no problem and no issues for the remainder of the drive.Now, before I start playing whack-a-mole ( as another member quoted in another post I read trying to find a solution ) what am I looking for....a vacuum leak? is it an a/c compressor issue? idle control sensor? MAP sensor?...its not the alt/battery cause it checks good...maybe because the jeep had no battery connected for one day waiting for the alt to arrive I need to reset the ECM??? I hate the fact that auto manufactures made new cars so complicated with all these unnecessary electronics that the common man has to have an auto degree to diagnose/repair their own vehicles.Oh...one more thing and this may be related..I had changed the PCV valve and air filter a couple months ago and noticed a vent hose on the side of the air box and that small filter was hard and crumbled when I removed it.Called the dealership to get a new one....no luck...didn't even know what I was talking about.Long story short I made my own using a Briggs and Stratton filter.Seems to work fine but there is quite a lot (to me) of oil?leaking from the box.Seems kind of excessive....not familiar with this.Cause for alarm??? Hope someone can shed some light on my problem because I don't really want the wife taking it to the mechanics because I know they will charge her for 4 hours of troubleshooting when they probably know what the problem is as soon as they see the situation.Any suggestions would be greatly appreciated.