Fuel injection cleaner made check engine light flash?

I have a 2000 mazda 626 w/127,000 miles on it which i puchased 3 mnths ago. The manual says I should use 91 or 92 grade gas but i usually use the cheap stuff. Occasionally I splurge & give her the good stuff. But can using the cheap gas ruin your car? About mnth ago the check engine light comes on & I put in the good gas & 1 day later lights off. 2 weeks ago it feels like its sputtering especially when trying to go up a hill (I really have to grind the petal to the ground to make it go faster) & while sitting at a light.I got fuel injection cleaner put it in, my check engine light comes on. I wait 2 days it goes off. Then about 4 days ago I start driving, turn on the ac & the whole thing starts vibrating & I can feel the sputtering or lack of air again & the check engine light starts flashing like crazy. Everyday it flashes now even w/out the ac on. Now when the phantom check engine was coming off & on 2mnths ago the mechanics couldn’t find a reason for the sputtering (my bf swore something was wrong & went 3 times to the mechanic in 1 week) & said everything looked fine. Either my bf is psychic or he broke the car bc he was obsessed w/fixing a problem that didnt exsist. Help please?!?

Take the car to a chain auto-parts store and they will “read the codes” for free. With a flashing CEL, there WILL be codes stored in your cars computer. Write the codes they find down (P0472 something like that) and post those codes back here. THEN maybe we can offer something other than guesswork…

Thank you.

A steady check engine light means you should get it to the mechanic whenever you have the time. Many people just ignore them and keep driving. You likely won’t damage the engine but will be polluting more and spending more on gas due to reduced mileage.

A FLASHING check engine light means something is really wrong. You either have a clogged injector/other fuel problem OR a serious ignition problem. Running it like this WILL eventually damage the engine over time, especially if you are getting fuel but no spark. This will wash down the cylinder walls with gas and also dilute your oil.

Give the car a good tune up and then fuel pressure test if that doesn’t fix it. You need to get this resolved ASAP, not a month from now unless you park it for that month.

Ditto above… The car is warning you it will leave you stranded any minute now.