What are my options for repair the engine idle is up and down and the timing advance is not working?

 

Your options are check the icm wires, est connection and continuity of the icm to ECM wires.
Having the icm tested or just replace it.

 

Code 12 is not an issue.

Start with a full tune up.

How do you know the advance isn't working?

 

I checked the all the distributor wires back to the ECM and the EST wire to the fuse block. Where the small white EST wire connects to the fuse block there is not a fuse. Is that normal? The wires are good to those points.
I replaced the ICM its still the same problem
I can't find a wire schematic for the distributor wiring. Do you know where I can get one for my 1992 5.0 tuned port injection engine? My book does not show the EST wiring.

The engine starts up, idles but will not advance and stalls out.

Any more ideas? Thanks for your help!

 

So how do you know the timing is not advancing?

There's no fuses near the dizzy for the dizzy.

 

I don't for sure but I do know that it runs really bad or stalls on acceleration. The code 12 says the distributor is not sending back info to the control module. The tune up is current it was smoking the tires. The next time I started it up the light came on and it won't get out of its own way now without stalling. Any ideas?

 

There is a white wire with a connector behind your passenger shock tower. If it is disconnected the ECU will not control timing.
Try checking this connection, it should have 5V when running nothing when cranking.
Watch a timing light and have someone connect and disconnect it, if the timing changes then the ECU is running the timing.

 

I am getting 12.5 volts instead of 5V. Any ideas why?