RPM Lag

[Mostafa]

hi. i have mazda 3 2008.
after drive for 10-15 mintues the rpm get lagging. ( when the lag start i lost a little performance on car - when pushing the pedal the rpm goes to 4000 but after a sec goes to 3700 without change the pressure on gas pedal)
video

if i turn off the car for whilethe lag gone. but it become again after a long drive)

- i change the engine but problem not solved.
- no error code.
- battery replaced
- i cleaned the throw body + MAF
- my mechanic said i clean the EGR too. but i'm not sure. it could be from there?

do i need to replace the MAF or MAP sensor? ( no ODB error code )

[Mostafa]

could it be from transmission?

[G ~ MINI]

i agree ...perhaps Clutch slip... if MAP / O2 / dirty airfilter would trigger a CEL

[Mostafa]

UPDATE :::
if i don't turn on the AC then everything would be fine.

[Mostafa]

someone said this could be from bad knock sensor. right?

[TheMAN]

it's possible
it's also possible there's programming faults in the ECU... a dealer can update this to the latest one.... there's always bug fixes with newer versions

[Mostafa]

knock sensor replaced . but no luck. i think this mess coming from the air condition, but i dont know which part.