I hav a 96 Cavalier, the check engine light came on a few weeks back. Thought it was and maybe still the ICM. This mornin the car was running really rough and the check engine light started blinking. Any ideas on what exactly is wrong with it ? Could it be the ICM ?

Check for bad spark plug cables and check all the plugs. Take out spark plug cable one by one and crank engine to check if there is spark or not. Before you head over replacing expensive items in this car get a compression check by mechanic for each cylinder. For a car this old and so much miles on it, most probably it needs an engine rebuild.

You may want to check for fuel volume and fuel quality. There may be moisture in the fuel. It would also help to know which cylinders it is misfiring on. Scan tool will show the misfire on live data.

This sounds very much like the ICM is the culprit. This helped me once with the same problem: Disconnect battery and wait for a few minutes, then take the ICM out and the ICM-board out of the little cage and check for signs of moisture. If you find something, first clean the board carefully with circuit board cleaner. Then take a heat gun and treat the board with a lot of heat for a couple of minutes but be careful not to melt it Put everything back together, reconnect battery. If you're lucky the ICM starts working again.

Anyway for sure you should check the error codes with vida to see which modules also might be involved in the ICM shout down, could be the antenna/(radio) module too for example.
It's sometimes very strange what can help bringing faulty ICMs back to life. There is one magic trick I discovered that helped me last time and since then my radio never stopped working again: With the engine running pull the antenna fuse. Disconnect battery for 20 minutes. Put antenna fuse back, reconnect battery. Start engine and maybe your ICM is back to life.

Sounds like there is a blown piston, to be sure have a compression test done on that #2 cylinder, if the reading is low, then you'll know.
A friend of mine had a 95 that did simular things only a little more,
it started smoking, dash lights flickered, etc. Finally, he had to get rid of it, the piston rod went through the engine block.

I don't know if it would cause the shaking and vibrations, but for the smoke it could be loose nuts or broken studs on the exhaust manifold -- when engine is cold check each of the nuts (there should be 8) to see if they are loose or missing/broken; you may have to remove a heat-shield in order to gain access

What engine? When it has no spark it looses it on all cylinders? The first thing I would try is the crank position sensor.

Try checking the spark plug, and the spark wires, if that doesnt clear things up then try replacing the roter under the distributor cap and check the cap for any corrosen

Just a shot in the dark, but the oil pump may be going bad.

take it to an auto parts store and have a diagnostics test done

I have a 96 cavalier and if i forget to turn the gas cap until it clicks air gets in the tank and the ck. engine light comes on. So, don't forget that could be part of the problem