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I have two issues with a 2015 Civic, not sure if they are related. 183k kms, automatic transmission.

1) car jerks when accelerating from stop, around 1500 RPM

2) RPMs fluctuate while driving. Only seems to happen when the car is warm, after about 10-15 minutes of driving. Idles fine and when driving at constant speed and RPM seems fine but when more pressure is applied to the gas, the RPMs fluctuate. Not a gauge issue.

Car was in the garage with a CEL 7 days ago. According to the mechanic, DTC indicated a bad Knock sensor which was replaced. It was also noticed that the transmission fill cap was off and the fluid appeared to be contaminated so it was drained and replaced with new fluid. Car was given back but the two issues above were still present. No CEL since the knock sensor was replaced. Upon visual inspection discovered a tear in the air intake boot so that was also replaced yesterday. However, both issues still seem to be present, although the RPM fluctuating doesn't seem to be quite as bad but the car hasn't been driven a lot since to really determine to what extent.

Anyone have any ideas or suggestions on what to check next or how to proceed in diagnosing these issues? Would this be a transmission problem? Any help would be appreciated. Thanks.