My Alfa 156 1.6TS is missfiring
I have just bought a second hand Alfa 156 which is X Reg and has only done 34,000 miles.
Before delivery the car had a thorough valeting inside and out and now the engine is not running properly. On the test drive it was perfect so it must be related to the engine washing.
My local garage has replaced the spark plugs because they needed it, but it hasn't cleared the problem! When I watch the tachometer on idle the engine misses every so often and there is hesitation at low speed when accelerating. Once I am into the higher gears it gets better, but it is really annoying. According to the garage the diagnostics are not picking up anything.
Does anybody have any ideas what is wrong?