My Volvo S40 1998 is misfiring when cold and although it gets better
with the longer I drive it its not right - after about 30 mins of
driving it seems to be ok although there is some shudder and
hesitation if I drop down gears and want extra power without being
smooth with the gear change! The revs seem to be very high when I turn
the engine on at about 1800RPM though that goes down to normal within
a few minutes.

I took the car back in September to Volvo who could not find anything
wrong but said it was most likely the fuel was too rich and the engine
management unit needed replacing!

But as far as I am aware it never once misfired while they had it! a
few days later I took it to another garage and again they could not
find anything wrong at all!

Yesterday it started doing it again - and I have booked it into a
local garage for monday but I am wondering what it could be that would
cause it happen then vanish then come back again! it seems highly
eratic!

Any thoughts? I can only assume that when thge garages had the car
they checked all the connections, plugs etc and cleaned everything
which may have helped? I don't know - I am not very technically
knowledgable about cars so please keep it simple if you have an idea
for me! Thanks.

Two more things quickly - I managed to knock the plastic passenger
side trim off my bumper - the bit that clips onto the bumper but I do
not know what it is called - or where I can get a replacement - I
would prefer to get it online and just clip it on rather than going
through volvo!

Also my driver side window has just randomly stopped working- it made
a clicking sound and now won't open or close? what is going on there?
when I press the button to open or close it the motor works but the
window doesn't move - all I can hear is the noise from the motor
working!