I am having an intermittent problem with my 2009 Scion xB (120,000 miles), but lately, it has been persistent. The only time it is fine is when I drive it the first time in the morning, and even then it is only 90% of the time.
When the issue is happening, I get the "VSC off", "traction control off", and "check engine
" lights on. The the whole car starts vibrating, like the motor is spuddering, and there is a hugely massive drop in power, huge. It sounds and feels like a cylinder just won't fire off (I also know nothing about cars, so that may not be correct). The headlights
will dim and brighten at the same rate of the spuddering. I can't get above 15-20 mph up a hill, and sometimes much slower and constantly decelerating while climbing. And when on level terrain, I can very slowly climb up to the speed limit. The transmission won't shift up automatically when the gas pedal is pressed down, and will actually down shift if I press down on the gas too much.
When the issue first started happening, it would come in and out. Like, I could go a week without an issue. But now it is persistent all day every day (except for 90% of the time after a cold start in the morning. The issue will sometimes appear while mid-driving after that cold start, but always always after I start it the second time of the day).