Have 99 that when you start it runs real rough for about 5-10 seconds then tach quits cel comes on and it smooths out but not drivable no power. This all started with no start condition Ecm was not turning on fuel pump.Replaced Ecm truck started but gave code for bad cam sensor so I replaced it and it still gives that code and same problem. All sensors have 5 volts all grounds are good put in new crank sensor. I have now replaced the ecm again and the cam sensor with still the same problem. The crank sensor showed no damage this is driving me nuts

Your truck should have both a crankshaft sensor (behind the starter) and a camshaft sensor (under the vp44). Which one did you replace because it sure sounds like a camshaft sensor...

I agree with Cumminz.  I am guessing you have an issue on the crank sensor.  

 

What did you replace?

i have changed both and camsensor twice 

Ok,

 

you said you tested the wires?  

 

Tested for 5v from the ecm?

tested for Grnd?

tested for good omh from the pin at the ECM to the signal pin at the sensor?

We'll have done that all checks ok. Changed crank sensor agian today same problem

Whats the code?

P0341

So you need to pull the ECM plug and the Cam Sensor plug and ohm from end to end to see if there is any connection problems. This test should show 0 ohms but 0-5 ohm is acceptable. Then while its disconnected ohm from pug to ground looking for shorts to ground. So on this test everything should be infinite ohms or OPEN.