Fuel surging?

Better description of symptoms, how , when , where etc or not?
Video/sound of tach when acting up?
What APPS is on it. factory, Timbo or other?
When it will not start does the WTS light come on immediately with the key every time? It does not need to stay on when warm , bu should flash on a second every time.
Pull codes with a scan tool.
It should start every time on first turn.

If the tach stopped working, get a new Crank shaft position sensor. It goes in the side of the block behind the starter. Starter removal required but not hard. Soak sensor with WE40 first, remove boolt hold down.
Soak, twist and pull out. Pull or pry gently, do not brake the plastic.
If tach stopped or went crazy, it is bad and replacement. Most likely will fix all issues.

Does it fail to start until the WTS light comes on for a flash or more?

It the wait to start light does not come on immediately every time you turn they to ON and it will not start at that time the ECM is bad and needs replacement. ECM bad is likely causing other issues you are having. Best replacement is used from running wrecked truck. From here or car-part.com( wrecking yards or CL. $200-600.
any from 98.5 or 99 will fit, 00-02 will not. Double check part number on unit.
Do this first and see if it fixes everything.