560 sec changed on kickdown but no power

[BO'H]

Hi,
Hopefully someone can assist:
My 560sec is lacking power. Now, it has stood for 7 years and i am only 300 miles in to blowing the cobwebs out of it and this includes using fuel additive to clean the injectors but she is v sluggish and on kickdown, she changes gear but then just hangs there and does not surge forward. I have to let off so she changes back into the gear she was in for her to pick up speed. There is sometimes a misfire at that point but not always and in fact happens less now. She maxes out at 100mph. She has had a full service including distie cap, rotor arm and plugs and fuel pump. She is running weak, due to needing to reduce hydrocarbons for the MOT, and i have been advised to keep it that way whilst the additive gets to work. I know the cylinders are all ok too.
The ASR light is on - could this be culprit?
Thanks in advance,
Benedict.

 

[BO'H]

A mechanic who knows these cars said it may be the throttle rod linkage but this part is not available anymore for my 560SEC with ASR.

 

[LostKiwi]

You need to get the diagnostics read using STAR. ASR being lit will kill the throttle response and reduce throttle openings by internally adjusting the linkage in the throttle body.

 

[BO'H]

Interesting - thank you. Have to say i have just manually moved the throttle linkage and it seemed ok. At the pedal end though, things are drastically different with the inch or more of play. I did not realise the diagnostics could be read on machines as old as these. Thank you.