Cb radio install issue

Some time ago on my old 01 f250 7.3 diesel. I installed my first cb radio(cobra 19 dx III) used from eBay and it came with a 3ft magnetic antenna. Installed it and it had terrible range and a large amount of interference coming from the engine. And it basically sat unused as nearly every thing was mixed with static.
A year or two has gone by since my trucks install and my wife's Jeep came with a cb radio and a tiny ant forget the model radio. Anyways comparing the two I knew the one in my truck had some big issues. After a bit of attempts to fix my issues. My trucks setup is better then the beginning but far from perfect

I've since bought a new 4ft dual antenna, cable, tow mirror mounts(not spaced at properly at 102" but at 84" ) and a new microphone. Other then that no mods that I'm aware of to the cb.

Switching the antennas from the original I definitely can receive much better.
But in testing my swr seems to high. I can't seem to find a good open area to really goto and do a accurate swr check. But in a area with RVs, trees, and mobile homes. My swr is around 3 on 1&40 with the truck off.
Any excess wire is in a figure 8 about a foot long(swr went from 4 to now 3)

Both antennas mounts are grounded to body, antennas are properly isolated from grounded mounts, radio chassis is grounded to dash.(swr stayed at 3)

As for powering the radio ive added and since removed a audio power filter to try and remove what I think is alternator noise, can't hear it during idle or coasting.
Even went as far to hook the radio to a entirely isolated battery.
Both the isolated battery and power filter had no detectable effects.

I'm starting to run short on ways to resolve my issues, any ideas?

 

I was just starting to think the radio was messed up too. But I wasn't ready to call it out until I had at least some else besides me calling it out as a likely defective unit

 

Mike my antennas mounts are properly grounded... Sorry it's in that first long detailed post..

 

I went with 4ft antennas to not rip the mirrors off at a McDonald's drive through. I gave up on using a parking garage with it. I just dumped some cash on a new cobra 29lxbt, I'm at the ends on getting my old cobra working well with the truck. I may actually bump the old cb over to a travel trailer. Nice to know if it's worth hitting the road. Without leaving the bed. Plus I won't have to deal with alternator whine in there.

 

I have already...... I seriously think it's a bad radio the antenna it shipped with had terrible reception for it's size, plus my issues wasn't just swr. Had a 1ft antenna on another cb radio that out preformed the 3 ft antenna that shipped with the cb I'm replacing. I figuring the cb radio was damaged from the original seller using it with a terrible swr. I probably transmitted from it 5x5 seconds each in a year. Or maybe something else
These cb radios really take a pounding during a life cycle. Heat and cold cycles can create microcracking of the solder joints, internal tuning pots can corrode and change values. A radio doesn't usually last forever. If the new radio has swr issues I'll probably run it to a cb installer.