low cold idle & idle rises when hot
 

1987 930.
Build is as follows:
Mahle 3.4L kit
K27-7200
993 Super Sport cams
Rarlyl8 exhaust
Turbokraft Intercooler
TiAL wastegate

After installing the intercooler I'm getting low cold idle and an idle that slowly creeps up when hot. Higher the hotter the oil gets - roughly 1200rpm at near 2nd mark on oil temp gauge.

Checked all hoses - OK (will recheck)
Checked AAR function - OK
Checked plug wires - boot on #2 was broken. Replaced. Plug looked OK. No change in idle.
Unless I'm misreading the IR temp gun the left side of the exhaust manifold seems to be quite a bit hotter than the right.
A bit of stumbling at low load through the RPM range.

vacuum limiter? What's the test procedure for this?

Ck o-rings at base of up-pipe to intercooler, they are sometimes cut on installation of up-pipe. Also if there is a hose from the intercooler to a BOV make sure it isn't leaking vacuum.

Only 1 o-ring left in the entire system - the one one the throttle body. It was a bit loose so I replaced it with a new o-ring. The up pipe from the turbo to the intercooler now connects with silicone couplers. Intercooler to BOV hose was good.

Seems to have fixed the RPM creep issue. Still low RPM when cold through and now I'm noticing hesitation under WOT and only 0.6 bar instead of 0.8 (yes, I know the dash gauge isn't the most accurate).

Going to check fuel pump fuses and relays when it's not 100 out.

So the Q has to be , what are the fuel pressures (on the WUR).
Too low a number on cold will give you that - sluggish rpm, then rising as warms. It is possible the WUR specs and idle mix are out. Assuming no air leaks.
Alan

One big problem was my battery was at 10V. A new battery (Optima 34R) ended up fixing the stumbling and crappy idle. Confirmed that the alternator is charging (14V+ at idle).

2 Chinese relays got replaced with the new ones from 914Rubber (and I just went ahead and replaced all of them).

Doing the valve adjustment, new plugs and wires and checking the distributor this week. Will also check the WUR.

Fouled plug was the remaining issue.

Unfortunately have to basically redo an entire major service from Eisenbuds in Denver as well as fix several new issues they created. That place is a disaster!