'91 Burb. Rough idle, stalling and a smell of gas

1991 Chevy 1500 Suburban, ~134k miles 5.7l v8.

He's (my burb) been sitting on my curb for about a month and a half, hasnt been run at all because the rear differential is on its way out. Last week I go to start it up and find I have a problem.

Terribly rough idle, probably about 150-200rpm? (I dont have a tach, so I cant tell) The whole body shakes and I can see the cabin lights dimming).

I give it a little bit of gas, and it seems to stop shaking (maybe 800rpm). If I give it too much gas (equiv to revving a 1100rpm), the engine stutters a bit, then stalls.

I tried to let it just idle a bit thinking that it would fix itself, but after 3-4 minutes nothing had changed. Smells like un-burnt fuel too (emissions)

My friend told me to short a box under my steering wheel to get a DIAG code, but it continued to blink "Hello".

Any help is appreciated. Thanks
-John