I was driving my 93 Bonneville down the freeway on Sat night when the engine simply died on me in the middle of a highway merger with no shoulder at 2am. I tried to restart but all it would do is crank but not turn over. The electrical accessories like radio, lights, power windows all work. Bonneville has 200,000 miles but has been well maintained. I've been driving since July without a hint of this problem. Previous owner mentioned having replaced some expensive electrical switch shortly before he sold car to me. The only thing I had noticed a week and a half ago was a slight jerking that happened only on two occasions. Any Ideas guys? Your help would be greatly appreciated. I like this car and can't easily afford another.

Sounds like the tall ale signs of a crank sensor. it'* an easy fix. check out this link

https://www.gmforum.com/mechanical-134/change-crankshaft-position-sensor-279066/

Check for spark. My guess is you have none. With no spark that means a problem with the ICM, crank position sensor, cam sensor, or a short in the ignition wiring harness. None of these are overly hard to change, but cost can be a problem. If it never starts, I would look at the ICM and ignition wiring harness. If it fires every now and then, could the the crank or cam sensor.

Thanks for the Suggestions guys will look into them
And to clarify slightly as I've noticed many have the problem of it turning over sometimes, mine hasn't turned over since it just shut off on me over the weekend. Had to get it towed twice already.

Just to be clear. By turn over, you mean fire. The engine is cranking but your getting no fire from the plugs.

Well It Cranks as in It Roars up like it'* about to turn over yet doesn't actually turn fulling on . Haven't checked yet for spark so I can't say for sure it has. I just know that before sat night I've driven this bad boy everywhere without it every having this issue once

So to clarify things more, the starter is turning the engine over, but it'* not starting?
If so, check for spark, and check for fuel pressure/pump priming.