Engine subtly lagging on highway.

[james.d]

Hello all,

 

Mazda bt50 3.2 is very subtly lagging  when on the highway. I can feel it and the rev counter sort of dips for a second.

Had the fuel, oil and air filters changed last year. 

Any idea to ask the garage to check also when l take it into them.

I only feel it on the highway and not around town.

Thank you.