Still trying to troubleshoot running problems with my 93 945T. When car is first cranked, idle will go to about 1600-1800 RPM for a few secs, then drift back down to ~500, then surge up and down a few times until it usually dies. If I restart and hold the throttle open for a minute or so, the car will then idle perfectly.

It's throwing three different codes indicating lean mixture: 1-1-3, 2-2-1, and 2-3-1 (I'm 99% sure those were the codes).

It sure seems like I must have a vacuum leak somewhere, but I can NOT find it.

Here's what I've done so far:

Cleaned, later replaced IAC (rebuilt unit)
Cleaned throttle body
replaced injector seals
replaced intake manifold gasket
replaced ~50% of vacuum hoses (remainder to be replaced this weekend)

There is no audible sign of a vacuum leak, and the remaining hoses look good. I have a strong suspicion I'm going to replace the remaining hoses and STILL have the problem.

Any other suggestions of what to check? AMM or O2 sensor? Plug wires, plugs, cap & rotor are all relatively new (<2 years).

Thanks in advance.

Hugh