As you have rated output on vhf and uhf, I would check the output of the ic7000 on a dummy load.? The radio may be folding back the power due to an antenna problem.
If it has full output on a dummy load, it is in the feed line or antenna.? The power at the 4 pin connector for the antenna tuner should be at about 12.3 volts or higher during transmit at full power.
This radio is very voltage sensitive, mine would shut off at about 12 volts.