Suspicious idle

I've had my G for a decade and it used to idle at 1000rpm now it idle around 500rpm and struggles to keep from stalling. There is no hesitation in accelerating but once it idle again it wants to shut off. I just changed the air filter, spark plugs, cleaned the MAF sensor and now it idles lower than before. Now I notice a difference in power but it idles around 400rpm now.

any help?

Check what was just done first, something may not have been done right.