I *think* that the sensor which is critical for alternator operation is one of the two temp sensors- IAT if my memory serves me right.

^^^

+1, thats what ive heard too.

There was no problem with the maf unhooked other than the code for "maf input low". The stock ecu still kept the idle perfect and the alternator must be still working because i've been driving the thing for a few weeks now and it fires right up every time.

FWIW my stock IAT is still connected but just sitting under the hood, not in the intake flow.

I just picked up a ODBII reader and the only CEL code I have if I read it correctly is a code for the MAF input low error mentioned by mikeflys. So when I go in for an inspection (several months away) I'll just plug in the MAF and clear the code. Hopefully that will do the trick.

So, to answer the OP, nope I have not had a problem with the crank position sensor error. MS-1 parallel install with a CAS.

If that is indeed the cause of my idling instability I might be up for some idle control. That being said, it is not too bad right now. I have it at about 13:1 and have the timing retarded in the idle region to about 11. Set up like this, it goes up and down with the A/C from ~900 rpm (a/c disengaged) to ~1200 rpm (a/c engaged). When the a/c is engaged it will run at 14:1 no problem. It also does this thing where if I come to a complete stop after de-accelerating, like at a stop light, it will idle at 1200+ for 5-10 seconds, then drop to ~900 rpm.

When I sit at idle for a long time, like 3-4 minutes it will get unstable again with the a/c disengaged. I think it is probably due to heat soak though I am uncertain of the exact cause and effect.

It is not a big deal so I can live with it for now since it is still completely drivable. I would not want to put the MAF back in the intake flow just to improve the idle. If just plugging the MAF back in helps then I'll do it.

It will be interesting to see if your idle changes with a no MAF setup Chad. I had assumed my idle tuning problems were only due to the big injectors.

I'm removing the MAF with the throttle bodies, so I'm doing the idle mod as well. As soon as the car is warmed up (ie idle in closed loop vs open loop warm-up), the idle starts to oscillate between 700-1200rpm without the MAF in there. I also get occasional oscillation when I let the MS control the ignition and the stock ECU controlling the idle valve, especially with the A/C on. As soon as I return the ignition control to the stock ECU, everything is golden. It doesn't matter if I use a flat ign map around the idle zones or I use a "valley" map, it's all the same.

Btw the idle valve frequency on my 2002 is 500Hz, what's it like on your '99?

Jim