Newbie With Engine Judders

[New to DIY J]

I have a 2002 yaris, when driven around or below 2000 revs the car judders and sounds to misfire plus when idle it sound rough, i've replaced the coils/spark plugs/lambda sensor/canister purge valve (vacuum valve) and had the air flow sensor check (which works OK) but no joy, it's been mentioned that it could be the throttle body or the fuel injectors.

Can anyone help?

Thanks J

[toyomaz]

I would give the throttle body opening a good clean with a liberal dose of carb cleaner it may be crudded/gummed up.

[Madasafish]

Sounds like one coil pack has failed

[New to DIY J]

I've checked all four coil packs and all are working OK, I will give the throttle opening a clean, thanks for the advice.

In addition unsure if this will give more direction to the problem, when the engine has warmed up and I'm setting off from a stand still (lights) the car seems to be lacking power and what sounds to be a whistling or high pitched squeaking then all of a sudden power kicks in and the sound immediately goes.

Thanks J

[New to DIY J]

I've cleaned the throttle opening, but no improvment.

When I started the car up (with the air filter unit back in place) the car still sounds to be gasping for air, like a intermittent vacuum, plus the previous issues.

Thanks J

[New to DIY J]

Could it be the o-ring on the throttle body?