Hi All,
I'm a complete newbie, so feel free to enlighten my ignorance.

Back story: Last summer my 1995 Toyota Corolla LE began having engine problems at a little over 200K. Due to parental pressure and the fact I drive about 300 miles a week on highway, I purchased a 2008 automatic Fit Sport with 140K. For the first six months, it worked beautifully, although I noticed the mpg was lower than when I purchased it. In December, I had the standard oil change and got a new battery installed because the old one was weak. That's when the issues began. It acted like it was going to stall on a couple occasions, and then on a 750 mile trip, I tracked my mileage and noticed a sharp decline in the mpg. One tank had 26mpg, while others had 29 - 31mpg (down from at least 35mpg).

On my return, I hit a large piece of road debris. It messed up the bumper and had to be repaired. When I picked up the car, other than the shop neglecting to plug in the air intake sensor cable and not having the front spoiler attached correctly, everything thing seemed fine. (I'm not going back there again - if they can't fix the obvious, there's no telling what they did inside.)

Anyway, immediately after, I began having constant stalling issues. Research tells me I'm not the only one. It's the standard problem - The car runs rough at first start, then tries to die at the first or second stop. If it dies, it starts back up immediately. Keeping my foot on the brake and revving the engine seems to help it not die. Once the engine warms up, it's fine. But the MPG is still not good.

First I ran a bottle of Techron through it. It helped a little, but not enough to stop the dying.

I took it to my local mechanic. He said it needed a new spark plug & coil on the 3rd cylinder. $200. Not happy, but I let him do it. It worked fine for a few days, but still a bit rough. I chalked it up to it still working the Techron through the system.

Then the engine light came on one morning. Took it to O'Reilly's. P303 - 3rd Cylinder missfire. Now I was mad. It died that same day. Late that evening, when it was really getting cold (15f as apposed to 30), the engine light went off and remained off. But it's still dying.

My mechanic from back home said it may be the IAC valve and that I could probably clean it myself. I've done a ton of research and I think I could and plan on cleaning the throttle body while I'm at it. I've done a lot of tinkering with other things, so auto work would just be an extension.

My other thought is that the EGR valve/chamber may need cleaning. That gets a bit more intimidating. I purchased to BG44k since it seems to be highly recommended. Would that help with the EGR system?

Also, how likely do you think it could be the valves needing adjusting? I've seen the DIY, but it's intimidating for someone who hasn't done much under the hood work and I'm not exactly loaded with cash. Places around here want $139 (dealer) to $225.

I know this is long, but any help would be appreciated.

 

Stalling?

Never had that happen with the ignition coil issue. I'd replace all the ignition coils and spark plugs instead of only one. Don't pay mechanics to do it, it's a simple plug and play job (OEM Hitachi coils cost 50 bucks at Rockauto) and just plug them right in.

200 dollars will get you all four OEM coils, and the labor is 15 minutes at most.

There's a good chance the mechanic replaced it with some cheap 15 dollar coil that wasn't going to last you.