GMRS Receives Crystal clear but transmits mostly static

[Guest Andy H.]

So I am a total noobie to radios of any kind. I got a small Midland MXT105 Radio for free and decided it would be cool in my 4Runner. I also purchase a ghost antenna, 6Meter NMO cable, and mount. I already had a power cable going to my under seat air compressor and so I tapped into that with the Midland power wire, and now I realize after reading some that it should have gone strait to the battery. 
I ran the cable for the antenna through the firewall, across the engine bay, up the side of the windshield, and attached to my Aluminum full length roof rack near the front corner of the roof using a steel mount from midland.

The radio powers up fine and can receive from handheld Gmrs radios a completely clear signal (I haven’t tested at distance, just within 200yds or so) but when I transmit from the unit in the 4Runner the handheld cannot hear anything but a little static and occasionally the end if a word or two. 
 

Is it possible that it could be the Power connection feeding back when transmitting since I have the radio in line with the compressor power cable (which is not powered on)? Is it the placement or lack of ground plain for the antenna on the roof rack?
 

I tried swapping out the antenna for the one it came with that magnets directly to the metal roof, and this made no difference (I moved it around to different locations too). I ordered a new Mic cause I thought that might be it but haven’t tried yet. Any help would be greatly appreciated from the experts on here. 

[SteveShannon]

I doubt it’s anything to do with your power cable. I wouldn’t even change it. 

Since the mag mount made no difference I don’t think it is your ground plane. 
Maybe the problem is the other end. Are both radios set for either wide or narrow band?  They should match. 
Finally, I would try talking to a different radio. If the static persists then you have ruled out the other radio.