first hello as im new and dont want to sound impolite
ive a focus 1.8 lx zetec engine thats using fuel and throwing a bit o whiteish grey smoke out the back. good compression runs lovely
now sometimes whilst changing gear revs are high then drops back down seems to happen till engine warm or a good 10- 15 mins ie slowing down waiting at lights etc

ive checked dtcs on digital dash didnt throw any faults up so plugged in me obd4000 diag on me lappy to which that also threw up no faults
reason i have obd is because previous garages ripp off bils to check other cars ive had
also cars not using oil water etc so am asking here firstly before costly bills entail,and since cant get a fault code im at a loss
many thanx