Started my 16v up this morning drove 2 miles and switched it off, then was really reluctant to start. Once it did it was missing but off idle under load. No warning light, popped the bonnet and checked plug leads, coil connection and distrubutor connection all ok. Spark plugs changed 2 weeks ago for the same problem.Only seems to do it if left a few days. Now it's decided it's going to behave itself which is great but not when your trying to find the fault. Any suggestions woukd be good.