Hi Charles. Unlikely this is caused by extra feeders. If you disconnect the extra feeders do the coaches still flicker.
Does it happen on all of the four tracks? If so then the problem is with the coach lighting. Make sure the connection from the pickup in the first coach is Ok and that the currect conducting couplers are also connected properly.
Do all coaches flicker or just some of them? If just some check the ground on those that flicker.
Make sure the track is clean if flicker happens only at the same part of the track.

David

Hello All. I am still working on the above problem you were right David I put the loco on the lower level and the lights still flicker .Today I have installed a 73140 light kit in a 43584 BI level coach why can't all lighting kit be so easy as that one

Hi Charles. 73150 is probably the best of the lighting kits.
Most of the trouble comes from the various connections going from coach to coach.
Current conducting couplers are not great with flimsy connecting parts...although they do work given time spent with them.
There are two pole current conducting couplers available but they are very expensive and only couple and uncouple by hand but you do get flicker free lighting.
If you have many coaches coupled you can have a pickup shoe at each end thus getting power from two sources which helps with six or more coaches.

My own view is take the power from the loco either with the two pole couplers or with the single pole and a ground on each coach. If coming from the loco attach the wire to the coupler from the track pickup going to the decoder.

David

Charles. Marklin make the two pole couplers but they are different to the single pole in that they only couple by hand. They are about 15 euros each.
If you are putting a pickup on the last coach I would put it at the beginning.
Do you have your coaches running flicker free now.

David