Gauges not functioning right.

The check engine light will require you to pull the codes to see what's causing that problem. The oil and coolant sensors are a different story. They should remain illuminated if you unplug the sensors, so the issue is finding the reason behind it. If it's your low oil or oil pressure sending units, one of those is probably bad and needing replacement, as long as you're verifying that the level and pressure are up to snuff. The low coolant sensor always tripped in my 90 before I got rid of it. Had it for 3 years with the same recurring problem. What I used to do is remove it, clean the contacts with some sandpaper, make sure the level was high enough, and toss it back in. If your cooling system is in need of a flush, it will usually cause the problem to come back much sooner because a good amount of sediment, etc will accumulate in the overflow tank and gunk up the sensor contacts again.