I have a 2.0 d 2007 sovereign, on acceleration i get a cloud of black smoke , is this normal, also when just cruising, say at 50 in 5th gear the car seems to be misfiring. i have no loss of power and it never happens at high revs, a further problem i am experiencing is sometimes (a lot) when in neutral the revs will not exceed 3000rpm, is this normal/?. please help, yours, concerned