I have a 92 Camaro and recently it has started dying within 3 seconds after starting. It's not consistent it does it off and on, however once it gets going and I start driving around it never dies on me while driving.

I have had the EGR replaced, o2 sensor twice, Fuel pump replaced. The EGR was the most recent one and my mechanic double checked for any vacuum leaks and couldn't find any.

My thoughts are along the lines of a dying IAC Valve or the MAP sensor, possibly a plugged fuel filter which I've never replaced, as the issue isn't consistent enough and seems like something bugging out from time to time. Any thoughts would be great!

 

Since it's a '92 (lucky you!), then carb issues can be checked off the list?
Assuming close to 200K miles? but I don't think mileage matters here, compared to years in service.

I would guess ignition module and/or coil

 

A '92 RS 305 would be TBI. Unless it has been converted to carburetor sometime in the past, this can be written off.

I doubt it is the issue, although if it needs to be replaced, it could be giving your fuel pump the hibby-jibbies. I'd recommend replacing it, just out of general good maintenance practice if nothing else.

Very often what may seem to be fuel problems are actually ignition problems. These are known weak components from the factory, so that isn't a bad line of thought. The intermittent nature of the problem does make it more difficult to diagnose, though. But if you replace one, replace them both, because either one can make the other go bad.