05 F150 5.4L 3v

I just changed COPs and plugs, cleaned the MAF and throttle body, changed fuel and air filter, and check valve. When I fire up the truck the engine, the engine runs up to about 1500rpm and then goes to a normal idle and after about a minute the idle starts to fluctuate from normal to about 450-500rpm a couple of times and then the engine dies out. Who has a clue as to what's going on? Also, Crank Position Sensor has been changed. This is frustrating.

 

Did you clean your throttle position sensor when you cleaned the throttle body?