Misfire on cylinder 3?

I have a misfire on cylinder 3 and a random misfire. I changed the spark plugs, the wires, the coil packs, the injectors, the MAF sensor, and nothing worked. I changed the MAP sensor and that fixed the problem for about 2 days. I also sprayed either checking for a vacuum leak and the engine didn't pick up, so I concluded I did not have a vacuum leak it only seems to miss at low speeds like driving through town but on the highway, it seems to run fine. My check engine light stays on for the most part sometimes flashing but when the traction control light comes on my oil pressure goes up.