We have had a jerkiness/misfire problem on our Zafira. ?

We have had a jerkiness/misfire problem on our Zafira. It’s a 2000 1.8i. It happens at just the point the throttle is opening i.e. just as you have resistance on the accelerator. It’s particularly noticeable when you want to just keep the car moving in say a 30mph area. The car jerks quite badly at times. If you accelerate its fine, if you come off the accelerator its fine. It’s just that bit in the middle.

Tried the main Vauxhall dealer but they couldn’t offer any solutions and have tried a mobile tuning service, be good to hear from anyone who’s resolved a similar issue