Oil light and overheating when car stops

A few weeks ago I put 5 extra quarts of oil into my 2004 Suzuki Forenza. Big mistake, I know. It immediately had problems accelerating, blue smoke, and then the engine died. It restarted and I made it back home. I then learned a thing or two about cars, drained the excess oil and replaced the valve cover gasket (which had blown). The sparks plugs looked fine (I measured them with a spark plug measuring tool to check) so I cleaned those off and put them back in. After that it drove mostly well, except for one thing. After driving the car for 20 minutes or so, once the engine gets warmed up to about halfway on the temperature gauge, the oil light will turn on when I stop. When this happens the temperature gauge also quickly rises. When I accelerate again the oil light goes off and the temperature gradually cools. Again, this only happens after I have driven the car a distance and the engine heats up. I tried replacing the oil pressure sensor, but it still happens. The oil and coolant levels are fine, the oil has a normal appearance (not milky) and the coolant may be a little murky, but its hard to say. I don't notice any leaks. Eventually my check engine light came on with a code P0217 (engine over temperature), but this came on when my engine is cool, so I wonder if the first problem with the oil light just caused me to blow a temperature sender. I know this is a long question, so thanks in advance for the help.