Minor problem at startup
 

1987 NA 68,000 miles, well maintained.

I have recently had to stop driving my 944 daily since I am doing a 140 mile round trip commute each day. I still drive the 944 every weekend.

At startup when it is cold it now idles very low for about 4 seconds, then the Idle goes up to 1200 rpm and slowly drops to 800 rpm as expected. If I give it gas when it is idling low it starts to stall so I am assuming that it is running lean for those few seconds. Other than this it runs really well.

A couple of years ago I replaced the DME temp sensor, cleaned the ICV and replaced the oxygen sensor. Most other common replaceable parts have been replaced over the last few years - plugs, wires, coil etc.

Any ideas on why the idle is doing this at cold start? I am tempted to put the old DME temp sensor back in as a first test.

This morning it occurred to me that I was leaving the ac on. After starting it behaved better when I turned the ac off for the first few seconds. Maybe the extra load of the compressor is a problem at start up. I know the ICV is responding a bit slow responding. Next time I will start it with the ac off.