Engine stalls while driving.?

I'm currently driving my dads Mazda 6 which is a standard. To begin with there is a knocking sound from the engine (not particularly the engine but in that area) within certain rpms per gear. Today tho I turned on the car and while usually the car revs up to 2krpm at ignition then falls down to roughly 700rpm at idle...this morning it revved up to 2krpm and stayed there as if I had my foot on the gas. On the way to work about 10 minutes of stopping at stop signs and making turns in 3rd gear (still going only 20 or so mph I feel the higher gears help fuel economy.) I was at a stop light and I put the car in neutral sat for a few mins then green light first gear and the car stalled...I thought to myself silly me mustve been careless (I never stall) but when i went to turn into my work in 2nd gear the car started to jump...as if the gear was too low....after work I drove home and I noticed when I take my foot off the gas the rpms fall to literally 0....and no engine sounds...but if i switch gears the car jerks and keeps going ( i assume this is "popping the clutch" tho i dont know exactly how to do that) Then my car actually started to stall in 2nd gear power steering out and even the "stall lights" (oil lamp and such) would come on. Any ideas? Its annoying and very inefficient to keep turning the car back on. Also it rained today could that be a factor to something?