car shakes slightly when starting to accelerate ( up to 2000 rpm). it almost feels like less power. sometimes i feel it, sometimes i dont. there is no check engine light. it feels like it looses power all together when driving, but that could be inmy head. any suggestions?

 

does it shake a bit when you're at idle?
My first thought was a bad motor mount but you say you feel a loss of power?

 

Check Coils and plugs. It's probably time to change it, but you didn't mention any of that.

 

yeah, if the car feels like it's shuddering while accelerating its' probably bad coils / plugs.
can you give us a bit more details?

what year is the car?
how long have you had the plugs, coils?
OEM cat?
original engine?'

 

i have under 40000 on it , 2004. the only problem is it sometimes doesnt do it. it idles fine. the most recent think i have done to the car was add the new greddy se exhaust in december. it the orig engine, orig cat, last summer i got new plugs (there was a recall).
the first time i felt it was after driving it on a really wet day, rainy and humid, but i have done that before and no problems. if it were the plugs, wouldnt a check engine light come on?

 

i have the exact same problem!

 

Mine does this!

I have no loss of power, but sometimes while at a stoplight and in neutral, the seats shake like they do when you have a bad start in 1st. Like that feeling/shake you get when about to stall.... I've had the car for 6 months, I have just ignored it... figured it was regular... so far no problems.

 

well i took the car into mazda today. the vibrations were from my after market exhaut they said, due to the fact it fits on tighter than the stock exhaust. I also had a ""loss of power recall"". strange.

 

is ur car an '05?

 

It's probably a combination of the a/c condensor kicking on (normal) and a cracked motor mount.
you still under warranty? If so, you could get the dealership to look at / replace the mount for free (I did)

 

exhaust causing vibrations?! WOW, can't believe they fed you that line...
which exhaust do you have? "fits tighter"?

 

greddy se

 

Its the motor mounts. Check that first, worry about your head issues later.

 

Sounds like motor mounts to me, although at 40K stock coils are living on borrowed time.