Reluctance to start-V6

[Bob Walker]

Dear All,
I really hope you are all well and that you had a good Christmas.
My V6 ZT has been behaving for the past few years. I recently had issues with a reluctance for it to start up and idle (it started spluttering into life and after a few seconds and a blip of the throttle everything is fine, it doesn't do this all the time) and on Monday after a trip back from York and a 10 min stop in Thirsk the car would not start. The rescue guy said the battery was OK and his jump started started the car and I got home. The next morning it wouldn't start and yesterday I replaced the battery. As soon as I did this it started first time and ran fine but this morning it took four/five goes for it to run and again the lumpy idle for a few seconds and then I drove to work and everything seemed fine.
I have replaced the spark plugs in the summer and replaced the viz motors with an updated pair from Stocktake as well. Is it a sensor issued or coils/ht leads etc??
Any suggestions will be gratefully received!!
Best wishes for 2022
Bob Walker