Carbon Build Up Again?

[is200 Newbie]

Parked the car on the drive on Friday night after work - have been in the garden all weekend - came to move it until Sunday night.

It felt a bit "lumpy" (felt it and heard it) slightly erratic idling when the car was first started from cold. Weather has not been cold or wet during the time it was parked up. No leaks and nothing else to indicate any problems.

I am thinking this may be an occurrence of what I thought was carbon build up which I had? previously with the car. Have been using a mix of Shell / supermarket petrol (more Shell than the other).

I have treated it twice with the BG additive in approx 3000 miles as I thought I would give it a good clean - it seemed to help but there's no pattern to the "eratticness" so maybe its just not worked.

Looking at other possibilities - fuel filter? Is this part of the service schedule or does it even have a filter? I don't see the point in putting it into Lexus as I explained above, there's no pattern to the erratic idling. The last time I felt this was around 2 months ago.

Any other sugestions (plugs / coil pack) - the idling settles down after a few minutes when just left to idle or almost instantly when driving - never had a coil pack go so would not know how it feels when they start to fail....

[ahmed24]

Does this happen with car on Drive, Neutral or Park?

[is200 Newbie]

Today it happened in park and I felt it when reversing out of the drive. Previously I have felt it when in drive when slowing down at a set of lights.