Engine misfiring. Spark plugs, ignition coils, spark plug wires, shitty gas??
My 2001 Toyota Echo (180,000 miles) started to sputter and shake when I started it to head home from the grocery store. (It was shortly after I had filled it up with gas in an unfamiliar station with high detergent in their gas.) I was scared to keep driving it, but I got it to the parking lot of a mechanic a few miles away, along the way my check engine light came on. I got a diagnosis from the mechanic there, and he said after running 3-4 codes that he thought it was 2 out of 4 of my ignition coils misfiring, and he wanted to replace those, as well as all my spark plugs. The parts are old and never been replaced because the car never had any trouble. The spark plugs and ignition coils are a really easy fix as far as I can tell, so I'd like to do the work myself. My only concern is how reliable his diagnosis could be. I know its entirely possible to have bad wires or a host of other problems that mimic my car's problem. I'm worried that I will replace these parts and my car might still not run properly. How can I tell what the real problem is? He also said that it wasn't misfiring while he was running it. Is it necessary to have to replace all of my spark plugs when I replace the ignition coils? Trying save money if I can. Thank you for the advice ahead of time.