rough idle

[panda30]

Hello everyone, my 98 s70 turbo all of the sudden began pinging on the way home,while I'm at a stop if I put in Neutral it smooths out like normal but as soon as I take off it like hesitates as if I were running out of gas.One im driving I feel just alittle hesitation..I replace the Mass air meter about 8 months ago and coolant sensor when they gave me trouble.Other than that complete tune up has been done around 6months ago. Any suggestions that I should check for..Well a couple days now a got codp0304 so I just replaced plugs after 10k mi and cleaned the Mass.The car is running like normall I drove 10 mi with no pinging.