What would cause my sequoia to loose acceleration ability momentarily?

You could have a throttle control issue, you could have an engine performance issue. One thing for sure: you can't just guess at it, only by testing can you confirm what is failing.

When your Toyota truck stop accelerating the dealership said that the "check engine" light comes on it was caused by a electronic safety sensor that detects a possible engine malfunction caused from a secondary air injection pumps and valves are bad. The bad values and pumps will have to be replaced in order for the "check engine" sensor to be cleared in efforts to restore the acceleration of the vehicle. So, since my truck is a 2005 and have the issue identified; I had the dealership clear the "check engine" error code to enable to truck to drive above 40-50 MPH and get it fixed somewhere else less expensive. The dealership wanted $3,200 for this repair (parts and labor).