Well I have made the decision that I have thrown too much money at this car in the last month of owning it to give up with the old girl, But my god is it trying my patience

List of new parts and things done to date (since 22nd jan this year) are as follows:
Cylinder head gasket repair that consisted of, 16 thousands of an inch head skim, new head bolts, all top end gaskets including valve stem seals, re-grind of all 16 valves, oil and filter change, new Gates powerGrip timing belt and tensioners, new water pump, full cleaning of the EGR and breather system (including throttle body and inlet manifold clean) and new head bolts!
After she was running again I then found other underlying issues with the engine so went on to replace the MAF sensor, air filter, rubber tubes on the coil pack, Thermostat and housing (then had to fit the old housing because of the new part failing), HBV as it was leaking badly and Then most recently had to fit the new radiator due to the old unit physically Exploding.
During the most recent repairs I found that the Gearbox oil cooler was leaking somewhere around the pipes that feed to it and had to top up the gearbox due to poor shifting and it being low on oil. I have still to get to the bottom of the gearbox issue as after 30 miles the rough/missed 3rd gear is back again!
Today has really cheesed me off ... Went over to town which is about 7 miles and noticed that theres a slight, what appears to be a misfire

It's only doing this at idle speeds and low road speeds but isn't throwing a code up or putting the EML on!
It's definitely a problem as it's impacting economy (0.2 gal/h to 0.3gal/h on idle and from 26mpg around town it's dropped to 24mpg)! Out of panic I have checked for any signs of HGF .. No oil in water and vise versa also not gassing back into expansion tank, I think that rules that out then

Now I'm thinking that it must be the camshaft sensor as it's the only other "real" plausible thing to do that hasn't already been changed (especially with it being a 2.2 petrol)! I'm completely at a loss really, Am I even barking up the right tree?
I really want to keep this car for a long time, but my god it's fighting it

Cheers Graham