Thank you for the email!
I would take a look at the attachments in my first response to this forum post, someone encountered the same problem as what you describe. These are helpful trouble shooting documents that will help you narrow down the problem.
Do you see the attachments?
If not I'll attach them here.

Basically, the Check Valve in the tank could have debris inside which is creating a bottleneck, also your small Bleeder Valve on the on/off pressure switch may not be "bleeding" the excess air out of the line and pump head after it shuts off.
Do you hear that loud hiss of air coming from around the pressure switch after it shuts off?
- MTR