280 SE 1984 mixture problem

[w126/280SE]

Hi all,

I have an 84 280 Se w126 Euro model with the pre-computer K-Jet system.

Recently I had a problem with a bad fuel pump relay which I replaced and now the car doesn't stall as it used to (scary at times).

However, I have a persistent mixture/cold start problem that seems to be getting worse.

When I first had the car, I replaced the thermostat, thermotime switch and egr valve, setup the valve clearances, changed and gapped new plugs (BERU) good cap and rotor arm, no tracking and clean. I would have a cold start problem, it would fire up instantly but the rpms would die off and eventually she'd stall. Applying throttle exagerated the problem. After a couple of attempts she'd idel at about 1000 rpm and slow down to about 800 when she reached 85 degrees.

The idle when hot wasn't silky smooth but no major wobbles or shakes.

Recently I was tearing down the road at about 80 mph and when she came to a rest, I noticed the idle was really lumpy and that the mixture seemed really rich. I have tried adjusting the mixture with a C/O meter but cannot get her to idle normally at all, and at the moment she's running lean under load as the only way I can egt even close to a correct C/O reading is by completely closing the idle adjust valve, and leaning her back to get her to idle below 1000 at idle hot.

I don't think this is a vaccum leak problem as it is an over-rich mixture rather than too lean. Could this problem be:

1. Bad warm-up regulator

2. bad fuel pressure regulator

3. faulty air flow meter

4. Cold start valve stuck open (removing the harness when hot running seems to make no difference at all)

5. Some kind of relay breaking down

6. None of the above?

Any of you experienced K-Jetters out there who have come across this before, I welcome any suggestions.

BTW, I put a new coil on her, no change.

Thanks,

Alex