I'd get that read next.
I have been having trouble with my car's acceleration (most prominently under load and on hills) for about a month with the issue increasing. The car runs fine at moderate speeds on flat roads ( motorways and such) but on hills the car reduces speed considerably even with the pedal flat to the floor. the thing I struggle with the most is that it is rather intermittent, one day its fine and the next I fear the car will stop moving completely. In search of remedying the issue I have had the oil changed, replaced the Fuel filter and air filter as well as having the cam belt, drive belts, water pump and coolant replaced. However the issue still persists. I am looking for any ideas as to what could be causing this issue.