Hello everyone, I have a 2014 Mazda 5 with about 135K miles. Recently she started shuddering around 30 to 40 mph. I thought it was possibly a transmission issue so took it to a transmission shop, while they were road testing it and had it hooked up they determined there was misfires on cylinders 1,3 and 4. I replaced all 4 spark plugs and coil packs, disconnected the battery. Took it out for a test drive, at first thought all was good then it began happening again.

Wheels and tires have been checked and rebalanced.

So has anyone else experienced this issue and if so do you have any suggestions.

Thank you