rough idling

Hi All, I am troubleshooting my 2008 C300 (170,000 mi) that has a rough idle until it gets up to temp. Seems like the engine wants to ramp up every 30 seconds or so and then calms back down. I have an Innova 5610 v2 scanner which is not showing any codes and there are no check engine lights...

When i start up after a few hours parking the engine struggles to keep constant revs This goes away after a short time yet now the car has started to misfire / backfire when i depress the accelerator pedal quickly? It still goes ok on motorway but is getting sluggish as time goes on. I have...