Engine shudders then kills

I have a 97 JGC with a 4.0 6 cylinder that started acting up recently. When you are at an idle and in gear, sometimes the idle will drop and the entire vehicle will shudder then the engine kills. If you hold the brake at an idle it will drop from 750 rpm to around 300 rpm then shudder. Sometimes it kills or it will return to 750 rpm and smooths out. It starts back up OK and it runs fine when on the road at higher rpms. It only happens at an idle and while in gear. While in park, it idles fine. Can anyone help me out here with a little advice?

Thanks for any help I can get!

Take it to AutoZone and get it scanned...Post codes

or idle it up a little could be timing tho or vaccum leak..if no lites are on in dash..

Sounds like a vaccum leak somewhere.
Check out all your hoses in your engine
and see if there's any disconnection.
If this just started to act up, your
"CHECK ENGINE" light should come on
soon.