CIS frequency valve--warm up reg. problems

[Ameer Antar]

The car is a '84 5000 turbo. I have been having lots of trouble figuring 
out what's up w/ my fuel system, and it's hard to get good answers about 
CIS systems. The engine performance just seems very poor, but there are 
times when it's very torquey and powerful. The engine has good compression, 
although it has 190k miles on the clock. I hooked up an air-fuel ratio 
gauge to the O2 sensor, and I found what was causing the problem. When cold 
the mixture is lean but when warm it is more rich. But the real problem is 
at idle, the mixture is extremely rich. Beyond 1/4 throttle opening the 
mixture turns lean and stays there until the WOT switch kicks in and the 
mixture goes rich again. I've changed most of the vacc. lines and intake 
hoses. I checked the arm-up reg. control pressure and it started out at 
55psi, when it should have been 25psi. It stayed at 55psi when hot. The 
spec is 55psi. There was 12V at the harness, but only 13 ohms for the 
heating element which should be about 17-21 ohms. So I guess I need a new 
regulator. Espensive...should I get used or new?

So that's the problem w/ the poor cold running I guess, but the other issue 
is uncertain. My best guess is that maybe the frequency valve is not 
seating properly and allowing fuel to leak back to the return line. This 
would cause a richer mixture at idle, but not at higher loads. I already 
checked the cold start valve for leaks but it's fine. Also, in the morning, 
I went to release the system pressure at the upper control pressure union 
on the warm-up reg. but there was no pressure, only a little fuel leaked 
out. Even though it passes the factory residual pressure tests just fine, 
it must have a small leak to make the system empty after many hours, but 
not after 20 mins. It could be the check valve or fuel accum., but at least 
it makes it possible for it to be a leaky freq. valve. Sound reasonable? 
Thanks for reading all this. I'd really appreciate any advice.

-ameer