Toyota Repair: 1999 toyota corolla misfiring, obd ii scanner, vacuum hoses

Question
I have a 1999 Toyota corolla with 225k miles on it's 1.8L gasoline engine and an automatic transmission. I recently had the oil changed at Walmart.  The car was running perfect as always before the oil change. On my way home from walmart I noticed it was skipping real bad and the check engine light was blinking on and off. The car was shaking bad as well....because it was misfiring I think. When I got home I did a thorough check of engine compartment top and bottom for anything out of place ie; vacuum hoses, plug wires, belts,etc. Everything looked OK. I'm a novice mechanic so I knew it could just be coincidence Walmart did my oil change about 10 minutes before my car starts acting up, but not necessarily.  I used an OBD II scanner to get these codes p0300, p0303, p0302, p0300 pd, p0302 pd, p0303 pd, o2 sensor and o2 heater. My knowledge of diagnosing and troubleshooting with an OBD II scanner is limited to....it's nonexistent. Any ideas about what this series of events along with the scanner codes I pulled means? I was also wanting to know what was the pd for at the end of the last three codes.....thanks. F. Davis.

Answer
Hello, those are all engine misfire codes, P0300 is a multiple misfire code and P0302, 303 are misfires for cylinders#2 and #3. Don't know how changing the oil could have anything to do with it but then it's wal mart so anything is possible. It may just be a coincedence but you could go back to wal mart and complain that this happened right after the oil change,in most cases the misfires are caused by worn spark plugs or bad ignition coil packs, each cylinder has a coil and they are known to fail . Toyota doesn't use the pd suffix but I think it means a pending code on your scantool.