No start after running fine?

I suspect you disconnected the battery to do the recent service. If so, you must perform a relearn for "minimum throttle". Until that is done, you may need to hold the accelerator pedal down 1/4" for the engine to start and run. You won't get the normal idle flare-up to 1500 rpm at startup, and it will tend to stall at stop signs.

To meet the conditions for the relearn to take place, drive at highway speed with the engine warmed up, then coast for at least seven seconds without touching the pedals.

The truck will not start at all. I have power to the injectors, and a light red spark at the plugs. Even using starter fluid, it will not fire. I have replaced the ASD relay and the fuel relay. I had no problem with this truck, until the alternator dropped to about 5 volts. I removed the Alternator, cleaned the terminals and put it back on. , then it showed full charge. I let the truck run for 20 minutes and shut it off. It has not fired since.

Next, you'll need to read and record any diagnostic fault codes. Chrysler made doing that yourself much easier than any other manufacturer. Cycle the ignition switch from "off" to "run" three times within five seconds without cranking the engine. Leave it in "run", then watch the code numbers appear in the odometer display. You can go here:

https://www.2carpros.com/trouble_codes/obd2/p0300

to see the definitions, or I can interpret them for you.

If there are no related fault codes, be sure you're pressing the accelerator pedal 1/4" during cranking. If that doesn't help, we're going to need a scanner to view live data. There's three key pieces of information we'll need. First is the "idle steps" the Engine Computer has placed the automatic idle (AIS) speed motor to. Normal is around step 32. If it's at step "0", minimum throttle hasn't been relearned yet.

Next, we need to see the state of the crankshaft position sensor and the camshaft position sensor. On my Chrysler DRB3 scanner, those are both listed as "No" or "Present". Both will be "No" with the ignition switch in the "run" position. They must both switch solidly to "Present" during cranking. Aftermarket scanners will have some similar terminology to show when those signals are being received by the computer. If one stays on "No", that is the circuit that must be diagnosed.

Don't overlook low fuel pressure. A simple squirt test at the test port is not sufficient. It only takes a few pounds of pressure to create a strong spray. As I recall, your truck requires around 45 psi fuel pressure. That should be checked with a fuel pressure gauge.

Let me know what you find.