Flashing Check Engine Light

You definitely want to get that to a mechanic ASAP. If the check engine light is flashing, it is recommended not to drive the vehicle as it indicates a severe fault. Do NOT keep driving it around in that condition as you are only making it worse by doing so.

I just learned that it's the ignition coil! THERE are multiple codes... P0300, P1294, P302, P305!!! Seller of vehicle claims he changed the front 3 spark plugs and I should be able to see that looking at motor...auto zone employee says not possible to see spark plugs without removing part of engine cover? How did this happen and could it have been done maliciously?

You CAN NOT see spark plugs by looking at an engine. That's simply, totally, 100% false. My guess is they changed three plugs and the rest still need changing, thus the issues you are experiencing. However, do note that all private party sales are "As Is", so it really doesn't matter what happens with the car. Once you've bought it, it's yours regardless of any pre-existing conditions that were not disclosed.

Make sure you check the injector harness which plugs in by the ignition coilds as they are prone to meting... Believe me It took me a month goggling etc and it was as simple as that. 6 inches of each wire was melted and arching between each other. I then hot glued each wire to coat it and then put black electrical tape over each. Van run like new again.... No sensors... I'm just saying start with the basics and check the hares where it plugs into the main harness Dodge put it right above the exhaust and should have put it up a foot higher. I zipped tied mine after up higher...

Never worked on a vehicle before. Is this something I can do myself.