1989 Volvo 740 GL

Took this 1989 Volvo 740 GL in trade for another vehicle, despite knowing nothing about Volvos. I was going to make this my everyday driver because it runs so well and doesn't leak or burn any fluids. Unfortunately I found out that when driving, it occasionally bogs down, and the check engine light comes on. It doesn't quite stall, but it slows down. For me to take it into my place of employment I HAVE to have regular tags, and I can not pass inspection with the check engine light coming on. It can be tagged historic in Maryland as it is old enough but then I would not be able to take it to work, which was the entire point. Brakes were recently gone through and $700 worth of repairs were performed, yet the ABS light still randomly comes on. At this point I just want to get rid of it and get the parking space back, so no reserve!
Pros:
Runs very well, starts right up even when cold (see video)No leaks and recent tune up and oil changeRecent brake service New stereoSunroof works perfectlyAll windows except passenger front workPower locks work perfectlyFun to driveCan be tagged historic and driven while figuring out the problems (I had temp tags and used it for short errands)
Cons:
Some electrical gremlin causes the Check Engine and ABS light to come on randomly when drivingCan not figure out how to read computerPassenger power window does not workFront seats have wear and tear
As you can see in the background of some of the pictures, I have other vehicles that I'd rather spend my time working on. But I would gladly take any answers as to why it is acting the way it is, and I reserve the right to end the auction early should I fix it and decide to keep it as my daily driver.
Video:https://youtu.be/6Ys7vdM-k1M