I changed my air filter, changed my spark plugs, ran 2 cans of seafoam in it. Still getting bad gas mileage, should I actually take the fuel injectors out and clean then?

Just plugs, or plugs + wires + distributor cap?

Outside of that, and making sure the tires are properly inflated, yeah; might be time to clean the injectors.

Plugs and wires. No distributor cap, all tires at same pressure. I figure it's time for new fuel injectors, car has 150k on it.

150k, yeah; probably time to clean the injectors proper / replace 'em. You already did everything I would've done, if my mileage went in the crapper. ('00 Civic, stock 4-banger. Still gets 30-ish mpg, and I drive with a lead foot.)

Could be so many things.

Need more details. When did it happened? exhaust leaks? Rough or abnormal idle? I don't know the motor but is it DI ??