Took my car in for rough running problems during the first 10 minutes after startup. Mechanic replaced the coolant temp sensor and then apparently adjusted the MAF. Was this necessary or should i be a little concerned on why he did this. After I got the car back I started running lean. All of a sudden when I hit the gas the boost gauge will jump but the car will sputter and hesitate, kinda like its not getting any gas. Any thoughts or possible suggestions? Thanks