Engine acted like it wanted stall at light.
 

Ok figured first time this happened I would pass it off as bad gas, but this morning on my way to work, I had to wait at a stoplight and while waiting, my rpm's drop from .850 to .400-.500 and the car acts likes it wants to die, then the idle kicks back up to 1400k and then goes back down to .500 and then back up and then back to normal range. I noticed it a few times in the past but it only dips to .750-.800 engine vibrates, but nothing like this before, I just had my spark plugs changed at the dealer and a new air filter.

Make sure the spark plug wire boot didn't come off one of the plugs.

^.....yep, and then if that doesn't cure it.......then it's time to tell us more about the car..............year, mods, mileage, have you touched anything lately?
If, not......after checking the plug wire(see if it's loose as Jon points out), then it might be coil(s) or possibly wire(s) time.

Well tonight on my way home, I noticed my car was lacking HP in 4th-5th gear, usually feels like it has more power to give around 4-5k in those gears, but also thought I heard some pinging, only for a few secs, drove around the freeway to see if I could hear it again but never did. I have my wife out driving now to see if she can feel a difference. My car is 2005 MT with 37,000 miles, all stock. I sat with my car running for a few minutes to see if it would try to die and never did. What are signs of the motor failing? Dealer wont check compression unless they hear the car pinging or the car stalls out and doesnt start. Also noticed my mpg have dropped went 20 miles on 1/4 tank driving mainly city roads. Oh and no check engine lights.

You mentioned that you heard pinging.... did it sound like a rapid tapping sound?
If so, that is another indication that the wire boot came off the plug.
Go through all the wire boots, press in while turning it back and forth.
If you hear/feel a click, then you know one wasn't inserted fully.

The pinging sounds only happened when I was pushing the car in 4-5th gear around 4k, sounded like a car that had to low of an octane.

Have you replaced your coils yet?

coils? or New renesis....

Nope, dealer said they would replace them under warranty if they were bad. My wife took my car out and said it was running fine for her.

4th and 5th gear at 4k ain't even close to pushing this car. BTW......just for grins, what octane are you using?

93 octane, just found my car was a quart low on oil, dont see how it ate that much in week since its never done that before, I have yet to top it up since I got it, of course im due for an oil change now. How do you get to the plugs, tried from the top but way to many things in the way, do you have to go under the car to check?

Easiest way is to take the wheel off....seriously.
It allows access to look right at them.

I also have 05' MT 37K mi.
I was having almost exact same issues.
I changed my plugs and air filter myself which definately helped, but didnt fix completely.
I had taken to one dealer Galpin Mazda shortly after I purchased the car last monh. (avoid at all costs, they suck really bad!!)
They refused to address the problems I was complainging about, same as you.

I took it to another dealer today (Star Mazda in Glendale CA)
They were very nice and looked at everything I had complained about.
They changed the coils, all motor mounts, and performed a TSB that addressed lack of power. Upon picking it up it now drives beautifully! It idles perfect has no hesitation. I could not be happier.

All work done under warranty with zero cost to me.

My advice would be try taking it to another dealer that will give you the respect and attention you and your car deserve.

I will look into that when I have a place to take my wheel off, my car sits on a slope but thanks for info.

Just got back after adding a quart, think I overfilled it but 1st through 3rd feels strong like always, but to me 4 and 5th just dont feel the same, got up to 7-8k in 4th gear and still felt slow, my wife thinks im crazy, she says its the same and that im just paranoid about the car or that im starting to get use to the power.

Now my car only has dipped below .500 rpm twice, first time I was waiting to pay at a toll station after thanksgiving , 2nd time was couple days ago, just the first time I saw the rpm go up and down then up and then back to normal.

I've taken the car to two dealers, first one replaced motor mounts no problems, when I brought the car back saying the motor/car shakes at idle still, they said thats normal, also others from the forum say thats normal. Brought my car back asking about my pedal that is making a creaking sound, dealer could not repeat and wouldnt work on it, so I took it to another dealership and found the clutch switch was bad, upon driving home, it starting making a different sound, called the dealership that did the switch and said not to worry about it. Well when I brought my car back to the original dealer for new plugs, I asked them to check the pedal, and they noticed the sound and replaced the whole pedal assembly.

Try a third one? :banghead: Jeez..they suck!

Where in Texas, I'm sure someone will recommend one for you.

I live west of Fort Worth, only other dealer is a good 30 miles away, and is owned by the same dealer who replaced my clutch switch (Hiley Mazda). Only others are a good 50-60 miles away.

Also is it normal to see the cream/milky substance on the dipstick/tissue when its almost 60 degrees out?