When I am driving along with my foot on the gas petal, the car slows down, it drags, (sounds like changing gears) then resumes speed all by itself. My friend told me he thought perhaps the gas was dirty and to get the gas filter changed. When I took it to the mechanic, he said my 2002 Toyota Camry six cylinder, automatic did not have a gas filter. The problems still exists.
Your car does have a gas filter, but it’s part of the fuel pump inside the gas tank and is not designed to be a routine replacement part.
It could well be the filter is partly clogged or the pump itself is failing, or an intermittent electrical problem is interrupting power to the fuel pump.
There could be other possibilities, too. Your mechanic is going to have to figure it out. But you may have to wait until the problem becomes more severe/frequent so that you can reproduce it for the mechanic. Otherwise he’s just guessing.
What else happened when you took it to the mechanic. There is no place to start. You have any one of about 100 problems. So the vehicle has to be scanned for error codes. Someone needs to check the fuel pressure, inspect plugs and wires, check transmission fluid, etc.
Some additional information might also help.
Is the car new to you? If not, is the symptom new?
Are you a new driver?
Does it maintain speed with the cruise control on?
Is your driving terrain hilly and curvy? Do you vary your gas pedal pressure to compensate?
I absolutely concur with Cig’s recommendations. I’m only trying to assess whether what you describe is a normal vehicle operation that you may not be familiar with. Often new drivers take some time to learn how a vehicle actually maintains its speed. No disrespect meant.