'04 Mazda issues...
 

I got my wife a used '04 5 door about 3 yrs ago. Since then, we have ran into almost non-stop problems. First issue has been the A/C working when it decides it wants too. We have also had to put a new tranmission in at 92k miles. WHen the trans shop was replacing they said the one they took out was already a refurb meaning this was at least the 3rd one it has had in 92k miles.. After we did that last year it ran good for a couple months and then started sounding like it was running rough. I changed the spark plugs, air filter and was gonna do the fuel filter until I found out it was in the tank. After these changes it still sounds like it has the flu. It runs good and I have not noticed any performance degregation but it just sounds really rough. This is only when you are accelerating. In park or neutral it will purr like a kitten and rev as high as you want it to go and still sounds great. Put it in gear and start accelerating or try to pass someone on the hwy and it sounds like crap. Today I noticed it is leaking significate oil from the oil filter cap so I have to check that tomorrow. Anybody have any clue on what could be causing the rough sound? It is a fluttering sound. I have an '08 4 door that I love but hers seems to be a different story.

"Today I noticed it is leaking significate oil from the oil filter cap so I have to check that tomorrow."

Man , check this out! I would do an oil change...........drain all the oil and then re-fill to the proper level. Seems like you got way too much oil in there. I fairly new to this car but that shouldn't be happening. I just change my daughters oil and filter yesterday. In terms of running rough, I assume you have no CEL lit, but I think I would go see if any codes are present, than maybe clean the MAF.

Yeah, the oil leak is on the agenda today. And you are correct, there is no check engine light on.