plane change in Amsterdam

We came the opposite direction just a few weeks ago with less transfer time and made it fine. You shouldn't have to go through customs; we went through security because we were moving from one terminal to another and still easily made the flight. Have a great trip.

I have done this before, but flying from Zurich to Amsterdam to catch that morning flight to PDX, and I was not comfortable with only 1 hour 45 minutes to get to gate for the PDX flight. My wife and I now stay overnight in Amsterdam at the Hilton right in the terminal at Schiphol and it sure makes everything a lot easier and less stressful, and the Hilton has a great breakfast buffet.

Also consider whether your flights are with the same airline (or airline group) which is generally more efficient. If so you should be moving within a secure area with no Immigration and certainly no Customs. Your luggage will be checked straight through to Portland, and the US does not have preclearance procedures in Amsterdam.
As a rule of thumb, any transfer under two hours can be cause for concern, but Amsterdam is generally considered one of the most capable international airports.

"...Also consider whether your flights are with the same airline (or airline group) which is generally more efficient. If so you should be moving within a secure area with no Immigration and certainly no Customs..." No matter what airline(s) one uses, you have to go through immigration at Schipol. The terminal is divided in half with an immigration checkpoint separating the two parts. One half of the terminal all gates go to/from Schengen destinations, the other half non-Schengen...like transatlantic flights. At Schipol the security screening for transatlantic flights is done at the gate instead of centralized area.