Truck has no power has pick at higher rpms. Will not go about 4,000 rpms. This happens in park or driving. When in park will almost die when you let off gas peddle. There is no smoke or anything from the exhaust. Will not pull hills at all. When you start up a hill at 70mph will be at 30mph when you get to the top. Transmissions kicks down an rpms jump to about 4k. Then makes a bad pinging noise & loses all power. Also seems to surge. Rpm gauge will noticable jump a few hundred rpms. I have replaced fuel filter, ignition module, throttle position sensor, mass airflow sensor, put fuel injection cleaner in fuel tank. Never had anything act like this truck. It sounds like is out of time, but is computer timed. The person that had it before had just done a tune up when I bought it. I have put less than 2k on it since that time. Any ideas?