shadow77

My 77 280 will run great then all of a sudden it will run extremely over rich, it wont idle when its cold because I have the idle screw in all the way or else when its hot it will Idle at about 2000, i'v replaced the AFM, tps, and the fuel press regulator, I have good fuel press. any advice

NismoPick

How do you know you have good fuel pressure? What's the PSI when running?

It sounds to me like a vacuum leak, or something wrong w/ timing.

-Check the fuel pressure w/ a gauge
-Check for vacuum leaks (really check, don't just look)
-Check timing

I would also hook up an air fuel gauge to see how rich it's running.

xxxfinchkidxxx

try you cold start valve

shadow77

I'v done a fuel press test with the car running the press is a 35-40 psI, I'v set my timing to 7 deg btdc still the same thing and, i also sprayed the hole intake and everything attached for vac leaks and found nothing. about a week ago I hooked it up to a 4 gas analyzer (this was when it was having a good day) my idle was a little rich but it would pass smog real good so...

sideshowbob

Should be 10 deg BTDC.

Check your EFI control unit out, try swapping it out or opening it and looking for bad solder connections, or kick it while driving to see if there's a noticeable difference). Check all of your wiring, starting with the grounds.
Edit: On second thought, just switch out your thermotime switch and temp sensor.