Have you tried unplugging the ICP and then cranking it? If the mechanic said your HPOP pressure was going to 3000PSI and hanging there it sure sounds to me like that is where you should start. Unplug the ICP on the front of the driver side head. Look inside the connector for oil. If there is oil in the electrical connector, the sensor is likely bad. The other possibility is that it may need IPR o-rings. Check the ICP and report back. We will get you going again, just don't give up on it.

Here is a picture in case you need help finding the ICP.