Bizarre Mustang symptoms

Today I had the spark plug wires and spark plugs replaced. Cost me $250.

The engine's still running very rough, but acceleration is better. RPM gauge shows 0. There are two dead wires.

Mechanic thinks its the ICM. Says they cost $300.

Is this thing hopeless?

This is what the mechanic is calling the ignition control module (ICM). I looked in my Haynes manual and don't see anything resembling this. It must be the problem, though.

He may not know this particular system well, he had to use a computer program to learn about it after I brought it in. But it's a prominent garage that been in business about 12 years.

First of all, the spark plug wires and plugs were so bad they would need to be replaced before any diagnostics could be done.
He told me at first he thought it was the coil, so he put in a new one and the problem persisted so that eliminated the coil from consideration.

The choices were then either a bad computer or bad ICM (the box in picture). We ruled out the computer since this box seemed to be affecting the performance of the engine when hit or pushed. Maybe a bad connection in the wire harness? So this box you call the CCRM, could it be the problem or should I keep looking?

All 8 of both were changed.
It seems to me there's a connection between the RPMs and the problem. I bought it used and the rpms in idle were always low (500-1,000). Since the problem began, the engine is unable to maintain the rpms in idle, and it carries over into driving. Now the rpms are always on zero and I'm driving with half an engine. Whatever maintains the rpms must be the problem. Bad computer?

Where to start...
A friend recommended his mechanic (who specializes in Toyotas) to me so one Saturday I took the Mustang to his garage. He replaced the coils, cleaned out the spark plugs, patched up the a/c & vacuum tubes. As I drove it home, I could feel it had more power and idled calmly. Unfortunately the RPM gauge still read zero while the engine ran (that bothers me). I let it sit the rest of Saturday and all day Sunday. On Monday I hopped in to go to work, and the engine wouldn't start. Not even a clicking sound. Late for work. Later that afternoon I called the mechanic. He said the problem had nothing to do with the work he did, suggested I recharge the battery, and the problem might be the starter. That night I charged the battery, next morning plugged it back in and still no response, not even a clicking. The mechanic wants nothing more to do with it.

On top of the problems with the Mustang, I've doubled my car woes by getting a Ford Escort w/ standard transmission as a back up. Two days after I bought it the clutch blew out. It'll cost $800 to fix. The guy who sold it to me won't answer the phone.

To rescue my sanity, I'm taking a break from cars and riding a bicycle every day. At least now I'm getting exercise.