Slight miss @idle 97 16v

[cwc2128]

Hello there recently got my wife a 97 2.0 16v 1 owner from new full history in dragon green, its just turned 128k it pulls to the red line in every gear strong as an ox no hesitation no miss

However when @ idle it sits at 950 but every 4-5 secs there is a slight miss (ber bum) and the engine jolts a little you can see the engine move and feel it when in the car is this the norm on a valver as i have had 2 or 3 and none have really ran that smooth.

I have replaced

plugs cap and arm
ran a tank with injector cleaner use v-power fuel.

cleaned gunk from around dizzy ,sprayed cap coil and leads with water no ark's

Does this sound like its slightly lean at idle or  a struggling injector.

ANY HELP..

[boneybradley]

I would check the breather pipe's first as these can split and cause crappy idle.....my fave one is at the back of the engine with a one way valve in (this has 2 green bungs that seem to leak)....

[cwc2128]

I have replaced the vac hose going to the ecu the hose on the rocker cover from the fuel rail and the short one at the front by the dip stick , were are these breather pipes exactly thanks..

[bsting]

My 97 16v did something similar to this at idle and had a flat spot at about 2000-4000 rpms when driven.
I went through everything you have done too with no result  plus new leads, coil, battery etc

Sussed it by replacing the #30 ECU relay with a new one.
And a mate recommended i fit a new crank angle sensor too....now done

Hope it helps