Bucking 2003 Toyota tacoma 115,000 miles

At first I thought it was old gas stored in the garage. On a 2 hour drive this bucking occurred at least 20x at highway speeds. I burned out most of that gas and filled up twice and added sea foam. Just replaced the fuel filter and so far 2x. Should it stop immediately? It does not stall, is easy to start. Never changed spark plugs, original.
Please advise, at dealership it checked out ok on their computer. Girls just don't know this stuff, don't want to be taken advantage of at the very expensive dealership. Thank you very much!