CB radio static

Ok here's a problem and I can't be the only one that has had to address this? Installed a CB in the 74 back in Nov. Had a lot of static. Called Cobra and we did some changes to the install. Here is a list of what we tried: Isolated the power. Double grounded the radio. Added electric noise suppressor in the power line. Installed stand alone power supply not connected to vehicle power (12v battery sitting in floor of truck). Grounded exhaust system. Rerouted antenna away from the truck (antenna on a table 18' from the truck but grounded to stand alone battery). Added ferrites to both power and ground wires. installed another radio. Sent the cobra radio back for service and found not problems.
The radios work fine as long as the truck is not running. With the engine running all you can here is static.
I've got two cb's that I cannot use in this truck. I tried my handheld (walkie talkie 40 channel cb with cigerette lighter power) radio and it works fine.
anyone else have problems like this that they have been able to solve?

What type of ignition are you using? What type of plug wires? I would try some radio suppression plug wires, if you have not yet.

Duraspark ignition. Not sure if the plug wires are or aren't radio suppression. I'll check tonight.

If you isolated the radio power/ground from the truck, then it's not dirty power. You've got something sparky happening. Probably either your ignition or alternator. You've probably got a lighting show going on with your spark plug wires.

I'll look into the wires again and check it in the dark. I'll change to a spare set of wires and see if that makes a difference.