Book of matches...
I have experience here through an ex-friend...they are money pits. I did a water pump in the sedan version, went great. Next day, the timing belt jumps not one tooth, but TWO. Not only that bullshit, but it magically jumped the wrong way. You'd think since the cam gears were dead-on even with each other, it was the crank gear that jumped a tooth forward. Not so - either it jumped 2 teeth backward, or both cam gears jumped 2 teeth forwards at the same time. And of course I get blamed for it, despite warning her the t-belt was past due after only changing a serpentine-driven accessory.

Anyways, it had zero power past 4k when I tested it, which I presumed it was only 1 tooth backwards at that time. Stupid me thought it was ancient plugs/wires and shitton of carbon from being driven by a pussy.
BTW have fun changing the spark plugs. They are under the IM runners, which are not bolted to the plenum - they use crimped metal bands. Horseshit Opel motor.