2.3 SOHC Code 42

Hello,

I have purchased a 1992 Grand Am 2.3 SOHC with 159K miles. I have a couple problems I could use some advice on.

First - I receive a Code 42 (ByPass or Electronic Spark Timing EST Circuit). I have replaced the spark plugs. Even though the crank shaft position sensor tested good, it was worn down on the end compared to a new one so I replaced it. The check engine light code 42 came on shortly after it was started prior to replacing the Crank Position Sensor now it comes on only after driving for a little bit.
Orginally I also had code 35 IAC Valve but I have gotten rid on it by replacing IAC valve. Compression on all cyclinders seems good at 228, 236, 230, and 230. Any Ideas?

Second is a idle problem - After starting it idles in park no problem, then when driving it idles in drive with foot on brake no problem. After driven then shifting to park it dies. However with A/C on it idles fine. Any ideas?

Also I have replaced all the vacuum hoses and do not seem to have any vacuum leaks. I have added a new Air and Fuel Filter.

Thank you in advance!