agh bogging like woah

okay so i picked up my car 2 months ago from some old guy for 2k. it has 140k on it n runs really well... when it wants to. its a 91 2.0t and the check engine light is on. we popped open the hood n saw that the 02 sensor was taped together, so i put in a new one. the light went off n it ran good for about a week, but sometimes on the freeway it wasnt boosting like it should. kinda splashes out boost. anyways, the engine light came back on and its starting to bog again.. a lot. it powers down and i cant go faster than 5 mph sometimes. just loses complete power. what the heck is wrong?

Could be a vacuum leak ... could be worn ignition components .. it could be both. If you just bought the car, I would start by getting a fresh ignition system from Toyota (Cap, rotorm wires and plugs). A new air flter, fuel filter and oil change. Get the basicis out of the way.

I would then check the codes to see what is tripping your check engine light.