Stalling, code P0106

For about seven months my car has been stalling occasionally, but it is getting worse. Recently a water leak formed and I changed the water pump, also when I did that replaced the timing belt and tension-er. When it stalls there dose not seem to be any specific trigger. It might do it at idle or when I am going sixty. Under power or when I am coasting. When not at idle it will usually recover and keep running if I put my foot down. It runs a little rough at idle but strong under power (when it is not stalling). The car is sending a P0106 error code. The car also got a new fuel pump a year ago. Please help.