Thanks again for your reply.

The pump does come on and runs for about 2 min on a cold start. The vacuum is also present on the line to the diverter valve. My next step is going to be to see if the diverter valve actually does what it suppose to and after that I will check the check valve.

The O2 sensor has about 40000 miles on it. What is the life expectancy of the O2 sensor? Thanks.