sputtering excelleration/ rough idle when you come to a stop

[1993zcandy]

I have a 1993 NA 300zx, and these are my issues

Car has sputtering excelleration periodically, and when I come to a stop the car idles rough for about ten seconds and then resumes a smooth idle.I take off from a stop It will bog down then go like a bat out of hell, if you keep the same speed it will run great. When you take your foot off the gas and then accelerate as you are going through the gears it will bog down again until you take your foot off the gas and then re-accelerate. My mechanic cleaned all the connectors, two had slight corrosion but the rest were fine. Gas Mileage is crap too, I need to get it smogged but im sure it won't pass with the intermitent sputtering. I also used Lucus injector cleaner since the car sat for years until l recently started driving it again. Did a 120.000 mile service as well. I have 75.000 miles on it.

Help.