Misfires and codes P0300 and P1684

We had bought the car listed above from a private party knowing that it needed the timing belt replaced which we did. But the moment it was started up it runs rough, and constantly misfires. It threw a P0300 code and a P1684. We replaced timing belt, replaced water pump, spark plugs, oil change, TCM replaced(old one was rusted through). Lived most of its life on a gravel road if that’s of any help. Cleaned ground chassis and reconnected it. Replaced battery. Cleaned ground wires coming from battery to the frame and checked all fuses in both fuse boxes. Car will randomly lose speed going up hill and will hear a loud popping from constant misfires. Door locks will randomly lock and unlock themselves. Seems to misfire between 2,000 and 3,000 RPM’s. No power locks at all. Key fob won’t work. And when opening rear hatch with key the tail lights will flicker. Idles really rough. Seems like there’s no acceleration and it has a rough time switching between gears, up shifting and down shifting. Headlights and high beams work. Until tonight the dash lights were so dim it could barely be read. And when trying to adjust the brightness level the dome light would come on right away no matter what we tried adjusting it to. Did this the whole time until now and decided to work correctly on its own. Think there might be a hole in the catalytic converter. That’s the next thing we’re going to check on. Any other thoughts or ideas? This is the only car we have at the moment so we need help in getting this fixed!