Truck? talking about the Police Interceptor Sedan or Utility? How many miles on it? Tuned?
Regardless, check the blowoff valves to see if the orange seal/diaphragm has ruptured. That can cause all sorts of oddball issues. Clean the MAP sensors and the IAT sensor. Check for pooling crud in the intercooler. Check turbo piping at the clamps for looseness/splits. check particularly the hoses connected to the wastegate solenoid atop the manifold, they come unclamped from factory, and can cause issues too.