Stop the parts cannon crap and figure out what's actually wrong with the truck. You can get a bidirectional scanner for $100. The APPS1 & APPS2 sensors likely are not bad; they rarely fail. There are articles about replacing with a Mercedes unit if it comes to that.
Parts in the system for throttle control:
APPS sensor pack, throttle body, PCM, and wiring harness in between. Also critical are ground cables and the battery/ battery cables.
APPS sensors - Apps1 should read ~0.4-4.8V on sweep from 0% to 100% throttle, with a smooth gradual curve. Apps2 should read roughly half that, ~0.2-2.5V. Apps2 will also drop to 0.0V on live data graphing; THI IS A NORMAL CONDITION. This is a built-in integrity check between the APPS sensors and the PCM.
FIRST place to start any time you're tryin to diag performance faults is the battery. Make sure voltage is ~12.5+ at off state. Check and ensure the terminals are clean and tight at the battery. Check the "other ends" of the battery cables. There are ground straps on the valve covers that push over the valve cover studs. Make sure they're clean, not corroded, seated properly. They're each about 3" long, and are there to ensure that the valve covers (and COPs) get adequate ground to the block. There's a ground strap at the BACK of the cylinder heads connecting them together too. All these need do be confirmed 100% solid and unmolested. Alternator should also be pumping out ~14.5V at idle.
Electrical gremlins are terrible for any vehicle and will kill your brain.
If the light's on, the truck is in limp mode. There will be trouble codes set. Again, get a decent scanner and figure out what the codes are. Again, AFTER you confirm all the power connections are good.
Look in the manual, or search GooXXX on a "ETC relearn". You can do this with just your foot and the truck's key.
Also, did this start right after it rained/ snowed/ you went off road/ hit a pothole hard? Did you fill the gas tank right before it started?
There are a ton of conditional impacts that can happen where no CEL will be set, but the truck will run like crap. You need to eliminate all causes.
Triangle of combustion: FUEL --> AIR --> SPARK
Figure out whether any of those three is suffering.
AIR - is the truck under water? NO - you probably don't have issues with air. That leaves FUEL and SPARK. Which of those two, or what combination, is impacted? Failing/ failed part? Loose connector? Squirrel-damaged wiring?
Also, don't be surprised if you have a broken valve spring. This is very common on these HEMIs. This is usually an "all of a sudden" condition and the truck will run like hammered sour crap. Scan tools won't show you this failure, but you can see tell tail feedback on a good scanner and with a good brain. A ton of work to diag this failure, but it's not a hard repair as long as it's just a valve spring.
Again, throwing parts without a scan and some real diagnostics is mostly useless...
