I have a 88 560sl. Been driving it for months now and it runs good.

Then last week something changed. I was driving and turned the radio off for a phone call. After turning it on again, it stopped playing, but the display was on. And I could not turn it off or change any setting on it.
Two days after that the battery seem to be dead. I charged it, and the car started, but with lots of trouble. Like it wasn't getting fuel. After it did start, the radio went back to normal. But the Idle is like 1600 in nutral and 1000 in gear. This Idle seems to occur after the car is well and warm, and cold starts are very hard. Also, my antilock light stays on since this started. My battery is at about 12 volts with the key off and 13.5 running so the alternator seems to put out.

I have read a few things on the board and have changed my fuel filter just to make sure. I tried testing the OVP relay and I think it passed.

I would like to run the diagnostic codes. I have a Bosch Injection book that tells me to start the test at the fuel relays. It just doesn't say where the relay is.
Can someone tell me where the fuel relay is in an 88 560sl?
Is there some good documents I can get on runing the codes and tests?

Can someone recomend were I can get fittings/guage for fuel presure tests? I have a GM/Ford style EFI guage.

Any suggestions on what to eliminate, and in what order?

The car just ran so good before this, and it survived Katrina.

Thanks in advance.

Dave