Let me start with some info:
-1988 S4 N/A
- has 25x,xxx + miles on orig. engine.
The car has been running perfectly for the past few years. Have not had any major issues with the engine at all.
Recently had a tune up: Spark plugs and wires. The coils were pretty bad looking so i replaced them with ones that were in good shape from my parts car. that was a few months ago, the cars been running great since then.

Today though I started my car, let it warm up to an idle ( I do this everyday since its winter and below 30 degrees almost everyday) everything was normal and good. Drove around town for about 5 minutes, I was accelerating from a stop in first gear and decided to rev it up to ~6k rpm for a few seconds. came to another stop sign and when I went to stop it didnt idle it just rev'ed down and died. Kind of like if you dont put in the clutch, except i had the clutch to the floor.

Now it wont start and when it turns over it sounds unnatural. It sort of pulses really rough as its turning over. I got it to start once and it ran extremely rough, like it was only running on one rotor. Sounded alot like a lawn-mower and the engine was shaking an extreme amount so i shut it off. Havent got it started since.

Checked the spark plugs for spark, they all spark normally. There was no smoke when it died or even when I got it to start. I havent been able to check the compression since I dont have a compression tester. ANy Ideas about what could be the issue??

 

You've already alluded to it. Check compression. 250k miles on an original engine... you've gotten your money's worth. Even if it were a piston engine, that's pretty damn good.

 

You need to start with the compression test ,, If you don't have a tester some part stores have stuff like that for loan or rent .. You could pull the plugs and turn the engine and listen for an uneven pulse which could indicate compression problems.. That is where you should start

 

I Kinda figured as much but I figured I would ask to see if there was anything else. Thanks guys, ill get back when I can get a compression test done.

 

If that engine has let go(god bless it for holding on like that) rip it apart and snap some pics, I am curious whats left of the housings.