Just read your request on your HF mobile woes.
Sounds like the feedline is not the issue.
Any car, boat plane that a HF radio is in with a 100 watts or so will get into "stuff" you don't want it in.
The grounding of your units is a major focus and should be # 1 before the radio is turnedon the first time.
In all of our haste to "Get on the Air" many dollars and efforts have gone up in smoke because we rushed.
I am stressing grounding because it is KEY to the reduction of resonanting circuits within your car.
Whenever a circuit is triggered by HF fundamentals or harmonics the source / entrance of the RF must be found and eliminated or grounded.
Your system is unique and only you can do the legwork needed but read the handbook about bypassing RF to ground with inductors and capacitors and you will prevail.
There is no quick fix or bandaid.
Check your grounding of major components between negative terminal of the battery and all points you think are "grounded".
Less than a .4 ohms is your target.
Use a Fluke grade digital meter.
Flat strap of copper or silver brade as wide as available is called for.
Ground your exhaust at three places 1 point being at the tailpipe and the other near the inlet of the cat converter.
Wide braid is needed to be flexible and RF effective.
Doors, trunk lids and hoods are needed to be grounded by braid.
On your tailights going on... do the above grounding first then see if the problem continues.
Be truly forewarned, the air bags can be as easily adversely affected as your tailights.