w124 220E engine not running smoothly

Hi,
Car is w124 220E '93 with 2.2 litre 16 valve type M111 engine with automatic transmission. This engine has motronic HFM fuel injenction system. Problem is here:
Sometimes engine is running poor when pressing accelerator pedal about 10% -> rpm's go from 500 to 1500 very regular unless you left engine to idle speed witch it runs fine. If you press pedal so much that engine reach 3000rpm there is never no problem, it's running fine on those rpm's . When this fault is "on" its impossible to accelerate smoothly because if you press acelerator pedal little bit nothing happens. When pressing accelerator more then car suddenly starts accelerating, this is very unconfortable on the road.. :(
Sometimes when running steady 55mph engine stalls like turning ingition off but if you press gas pedal immediatedly its accelerating fine unless you try to go steady speed it stalls again...
Car always starts very good when engine is cool or hot.
I take off idle speed control unit and put contact cleaner to the conponents, this helps a while (about 1000km), then problem comes up again. Below are links to pictures I take from idle speed unit. I think problem could be contact failure on that white round component because when putting a lot contact cleaner to the root of the axle car is running good a while. This looks you can do nothing to fix it because accelerator lever mechanism is welded on both sides.. Any ideas? New idle speed control unit costs about 600 euros (over 600USD) and it would be waste of money if only one component is broken but if you can't fix it you must pay..
Pictures of the unit:
http://img6.imgspot.com/u/04/234/12/idleproblem.jpg
http://img6.imgspot.com/u/04/234/12/idleproblem3.jpg
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I think it has to be the air flow sensor problem. Verify it before you start replacing anything.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Tiger wrote:

car is going to bosch service on this week, they will read out fault codes and will do a basic inspection for the car with emission tests etc. I think there is no way to inspect air flow sensor functionality except bosch engine diagnostic equipments?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
If you have the spec, you can measure the resistance... but other than that... yes, test equipment only.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Tiger wrote:

There was error code 21, voltage failure on idle speed control unit. Because of this fault in ECU memory idle speed contoller was not working at all and ECU was adjusting idle speed with ignition timing.
When fault memory was cleared idle speed controller starts working immediatedly! Strange problem, I hope this would not come very often anymore.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.