Can I border run to Vietnam and return to Thailand on a tourist visa after being on an education visa for over a year?

I guess you're not on a visa at all but an extension of stay based on education. You should cancel this with paperwork from your school before leaving

You can apply for a visa online. I have never had a ED visa but I have had a few questionable visas. I have been pulled aside at immigration a couple of times and each time, they said "when you come bacK...", not "don't come back" nor have I been denied entry.

You take a risk, so consider having a plan B. I would recommend crossing at a land border at least for the first time. This way if they deny you entry, you can walk back to where you came and try a different land border. Have a good story, you met a nice Thai lady and you're thinking about getting married, or something. Whatever the story, you will want to be able to provide proof.. Hence, if you go the girlfriend route, have a Thai lady friend available for the immigration office to call (it probably won't come to this but it's better to be safe).

Another thought, get a visa online, go talk to an agent about doing a border bounce (because you already have the visa you only need exit and come back). Agents often know which borders are easiest to cross and which immigration officers are friendly.

You run a very very high risk of being pulled aside at the airport and asked why you think you can come back to Thailand so fast after just living here for a year with an education visa.

Just having an education visa alone means you're probably going to be pulled aside and questioned any time you enter Thailand for the next couple of years.

But returning so soon after being here for a year is just asking for trouble.