Cyl.5 and 6 misfire causes

Hi, I'm one of the auto experts on RepairPal's Car Genius team! Great question! Sorry to hear that you are having engine issues on your 2004 Toyota Tacoma. There are several things that could be causing a cylinder misfire in more than 1 cylinder. It is possible that it is coincidental that they are right next to each other and you are looking at a a couple of bad spark plugs or bad coils. However it is also possible that there is something in common with those cylinders that is causing your misfires. A leaking or blown head gasket between those two cylinders or even a vacuum leak in that area of the intake manifold are also worth considering. I’d recommend having a qualified shop perform check the basics and then if they are ok, perform a compression test and coolant system pressure test on those cylinders as a starting point, as these tests can quickly reveal whether a head gasket issue is at play before any parts are replaced. Catching a head gasket problem early can make a significant difference in the overall repair cost. If you need any further advice or would like help finding a trusted RepairPal shop in your area or even getting an appointment booked, please feel free to call us at 877-913-1554 or check out https://repairpal.com/certified