stumbling 200.

[Larry C Leung]

After a day of intermittent power (felt good on no load, low speed stuff
in low gears (taking off from toll booths), bad in high speed, high gear
high load situations (up a long grade, long merges) I had some time to
check out the car today.

(Note, ECU replaced with a stock MAC 14 with the spring shimmed to an
indicated 1.5 bar, fuel pump did NOT
cut out when the LED display put up the 1.5 bar number).

1) Won't start when the air temp is cold, starts okay but will stall when
air is at room temp.

2) Large vacuum leak, i.e. dipstick test fails, and I can even lift up
the oil filler cap with
almost NO effect on the running. Was able to lift it enough to make
vacuum sounds.

3) Car is throwing a Oxy Sensor code, (2342) which makes no sense
considering its
able to run almost without hiccup when lifting the filler cap. How is the
engine compensating?

4) Not sure if this matters, and it's weird as I didn't rev it that hard
(couldn't) but I got an
overrev code.

5) Checked Intercooler, no obvious leaks (no oil under the end caps) and
MM hose, no
noticable change in the idle when heavily manipulating the bottom side of
the hose, no
oil under it either. Didn't have the time today to swap it with a known
good one.

6) Plugs look okay (tan) and rotor and cap look okay.

7) crankcase breather hose was removed and checked. A little cheesy stuff
in the opening
in the crankcase, even less in the hose. Cleaned out anyway.

8) all firewall connectors seem to be connected.

9) Car occassionally actually runs "right".

Any ideas (and any ideas where the ovacuum leak could be?)?

TIA,

LL - NY - frustrated '89 200Q