Hesitation can be a few things, obviously incorrect fuel mixture or poor timing usually. You say you've done a service so plugs, air filter, fuel filter should all be good.
I'd check/clean the MAP sensor if its covered in breather oil. Might as well clean throttle body too while you're there.
Temp sensor may be faulty and not sending the correct temp reading to the ECU - can test that with a multimeter I think.
Do you have the long coil pack, or separate ones? If its the long one, they are common to fail, and seem worse when cold, I had one fail and spike the ECU.
And as you say its only when cold, possibly a leaky injector, but that would also make it smoky and difficult to start when cold, so you can probably ignore that one.
I'd check/clean the MAP sensor if its covered in breather oil. Might as well clean throttle body too while you're there.
Temp sensor may be faulty and not sending the correct temp reading to the ECU - can test that with a multimeter I think.
Do you have the long coil pack, or separate ones? If its the long one, they are common to fail, and seem worse when cold, I had one fail and spike the ECU.
And as you say its only when cold, possibly a leaky injector, but that would also make it smoky and difficult to start when cold, so you can probably ignore that one.