Cleaned EGR Valve

[Grizzly350]

Hey all!
Been doing some research in order to find out some questions to my Jimmy's problems, and this seems like the place to be. It's a 94 with a 4.3 Vortech. In the beginning the idle was rough, it surged at lower speeds, didn't seem to start as easy as it should, and would spit and sputter after I shut the ignition off. Soon after it stared flooding badly and missing. I was told by my parts man to check the EGR valve. I cleaned it out and it seemed to help the slighest bit, but no big change. Now it still has all these symptoms, but gas is getting into the crankcase. As little as I know, I know what that will lead to. A local mechanic said he knew what it was when I described it to him and that he would repair it for $500.00. My concern is that with gas getting into the crankcase something worse than a $500.00 repair job is needed.
Can anyone tell me if and what specific part being bad would cause all these problems, and is it a matter of a simple part replacement to fix it?
My dream scenero is that it might turn out to be something I could do myself, but I'm not putting too much hope in that.
Thanks,
Robert

[GMMerlin]

Most likely what is happening is the CPI unit (fuel injector) is leaking inside the plenum (intake manifold)...this is not an uncommon problem and can be done by the D.I.Y. mechanic.
Basically you will need a CPI unit, Nut kit (fuel lines) and an upper plenum gasket.
Should take you an afternoon to complete the job.
Also change the oil and filter when you are done.