Well, after an expensive, tiring, and lengthy diagnostic process, the 232 is finally solved, and the check engine light is gone!!! It was the MAF, which I replaced with a rebuilt from Volvo for $390 including the trade in. A year later, and the below step by steps, it is finally gone.

1. Oil level too high Changed oil same

2. Vacuum leak smoke test leak in CAH, replaced clean air hose

3. Contaminated engine oil changed oil same

4. High/low fuel pressure injector cleaner, high test fuel same

5. Intake Gasket bad sprayed carb cleaner by gasket engine did not rev

6. Coolant temp sensor both replaced in aug 2005 same

7. Bad spark plugs replaced with Volvo plugs runs smoother, code returned

8. Sticking IAC (Idle Air Control) valve removed sprayed with TB cleaner, dried runs smoother, code returned

9. Oxygen sensor New Bosch 15908 02 same

10. Poor fuel pressure (weak pump/plugged filter/sock) Checked fuel pressure, ok same

11. MAF Replaced with used MAF code still there, runs rough

12. Tested original MAF with snap on tools, voltage ok, code still there

13. MAF Replaced with new/rebuilt Volvo MAF. Fixed the problem!!!!!!! Can't bloody believe it!!!!!!!!