Stiffer gas pedal after maintenance?

[TheAnswer_03]

I had some maintenance work done on my 07' Mazda3 (2.3L) done recently: new spark plugs, transmission flush, oil change, coolant drain and fill (switched to synthetic motor oil and ATF for the first time). Idle was very quiet and car was very responsive, but when driving it on a cold start for the first time the following day, the gas pedal felt very heavy and I had to apply more pressure to get it going even after car warmed up. Almost felt like driving with my e-brake engaged but it wasn't.

Idling RPMs was normal, no unusual sounds, no CEL or any other warning lights. Replacement spark plugs was the same model (ILTR5A-13G).

Am I just paranoid or should I get this checked out?

[TheMAN]

gas pedal "felt very heavy"? you mean you have to use more effort to push on the pedal? the gas pedal is just a piece of plastic attached to a spring and an electronic sensor! it is totally disconnected from the engine!

are you just saying the engine has no power?

[krimsalt]

What were the KM on the car before you put new ATF in it. At times, band clutches in the transmission get used to the older fluid and wear in to better work with the older fluid, when you put new fluid in it sometimes will cause that dragging feel you mentioned (like driving with parking brake up).

Also, on a cold day the cars do run a little worse I notice mine requires an extra push, but depends on how cold it is.

[TheAnswer_03]

Well hours later, I drove the car again and it felt normal. And then today I drove cold start and felt normal too but I wore heavy steel toe boots for the first time so that probably made it easier.

Mileage is 101,500km. When warmed up, car definitely shifts with more confidence (especially 1st to 2nd gear) and smoother as one would expect with synthetic ATF. The car idle is also noticeably smoother and quieter but that's probably due to the new spark plugs.

I used Royal Purple 5W-20 and Royal Purple Max ATF synthetic.

[krimsalt]

Yea my thought seems right, the transmission is getting used to the new fluid