I have a 2000 Peterbilt 379 with n14 celect plus. When u crank it , it barely idles (around 400 rpm) and is loping pretty bad, and it won’t accelerate unless u spray with ether and get rpm’s up then it runs fairly decent but won’t rev past 1700 rpm’s . Soon as rpm’s get below 1000 it starts loping again and won’t accelerate. It throws a 343 engine code at random times and goes back out. I’ve replaced timing sensor, fuel solenoid, engine wiring harness,and Ecm. I’ve removed belts on alternator and checked all grounds and hots. I have 12.2 volts at fuel solenoid, I’ve got a lot of time and money in this fix and haven’t figured it out and need a little help. Any help would be appreciated .