Randomly won't start. And also can stall at any speed?

Unfortunately they aren't the schematics for yours as a regular truck. Have no idea as yours is an rv cutaway and is closer to a van wiring wise instead of a pickup. For the stalling clean throttle plate on both sides and iac hole with choke cleaner first. Then check to see if intake bolts on engine are loose first pass should be 44 inch lbs, second the same third pass 89 inch lbs and final pas 106 inch lbs. Then if your pcm is out side where it can get water put dielectric compound where plug in to pcm is just take it out pack the stuff in there and put the plugs back in careful to not bend any pins. Your crank sensor should be where pic is at back of block.
NOTE: Care must be taken when removing the crankshaft position (CKP) sensor. Use penetrating oil and allow to soak around the CKP sensor before removing the sensor. Twist the CKP sensor to break the "O" ring seals loose. When removing the CKP sensor, pull the sensor straight out of the engine block at the same angle the sensor was installed. Failure to be careful may result in sensor damage.

Remove the engine cover. Disconnect the CKP sensor harness connector at the CKP sensor. Remove the fuel line bracket and retaining bolt. Use penetrating oil and allow to soak around the CKP sensor before removing the sensor. Remove the CKP sensor bolt. Prior to removal of the CKP sensor, twist the sensor back and forth. Remove the CKP sensor.
Fig. 11: Locating CKP Sensor (8.1d)
Inspection (8.1d)
Inspect the CKP sensor for wear. Important The CKP sensor is designed to contact the reluctor wheel of the crankshaft. Wear may be noticeable on the end of the sensor. Normal CKP sensor wear will be shown on the wear strips and no wear will be shown on the sensor sensing element. Excessive or abnormal sensor wear will be shown on the sensing element. If excessive/abnormal wear is present, replace the sensor. Inspect the CKP sensor "O" ring for wear or damage. If a problem is found, replace the "O" ring. Lubricate the new "O" ring with engine oil before installing

Forgot also check your fuel pressure with a gauge it should be 55-62 psi

Well there in lies the problem a lot of people mean when it doesn't start that it won't run. As far as not turning over that is why I included the drawing with the arrows on it on what to check. Also check your battery for condition including load test. Auto parts/ tire stores do for free. The yellow wire from your ign switch goes to neutral safety switch which in turn activates the relay so check those for corrosion or a like relay. Also make sure battery terminal ends are clean, meaning they have to be pulled off and check ed as they build corrosion between pole and clamp or bolt and battery. For the crank sensor check the wiring as it may also be another sensor creating the problem. The random stalling can be from a dirty throttle plate and or low fuel pressure that is why I included that in the first reply.