I still think that you have interference issues on RCH7 either from FM KSOS at 90.5MHz or from RCH2. Both of these are coming in very strong and probably overloading the amp or your tuner. You absolutely do not need an amp. You'll need to order some parts and follow these steps;
Parts: one 30 dB drop tap, one FM trap and a 75 Ohm terminator cap, enough coax cables to tie it all together.
Pick one of your antennas that does NOT have an amp, do not use an amplified antenna with the power unplugged. Connect everything like this;
<ant><FM Trap><30dB Tap><TV>
Between each <> pair you'll need a length of coax, so three cables and it doesn't really matter how long.
Take the 75 Ohm terminator cap and screw it onto the antenna input to your TV and rescan your stations. You should get zero channels, if you get any stations your TV is defective. Remove the terminator cap and connect the TV to the high loss 30 dB port of the drop tap. These connectors usually have three ports labelled IN/OUT/TAP. The IN port should connect to the output of the FM trap, the TV should be plugged into the TAP port, you should cap the OUT port with the 75 Ohm terminator cap. Make sure the antenna is aimed South and rescan your channels and see what you get. If my theory is correct, then your reception should improve and you might get RCH7 if the antenna you use has any VHF gain at all.
The FM trap and the drop tap will probably cost about $3-$4 and you might have to buy a pack of 3 or 4 terminator caps but that should be ~$2. If you find this all at the same online store you can probably save on shipping.