Hard start issues....again.

Are you getting a new 389 glider or a older 379?

The price of the old iron was pretty steep for a while.
If you got a 389 with a N14+ you'd have decent mileage and better power than Detroit. Traditional 355s on tall rubber with a 13 or 18

Hammer down and don't look back

 

Your first oem set of injectors probably had 2 o rings top and bottom. Do you remember what mileage it was that the first set was replaced?? I just did my injectors by myself this is first week back on the road. Soon will be doing test air in fuel with a clear fuel return lines just didn’t have time after I finished.

 

It shouldn't, but the motor is exposed to vibrations with jake on, especially the heads valves area.
Back in 2003 i blew a Volvo D12 , with 500k miles company truck going downhill with heavy reefer in Utah on I-15 , motor was not hot, after i turned the jake on heard some noises , vibration, that increased louder when i got to the bottom of the hill and motor stopped . I was towed in Salt Lake, @ Volvo, engine was destroyed, it needed new motor.
After this incident, purchased my trucks and very rarely use the jake , only if when i go west through rockies heavy, I didn't use it for years, i'm running flat roads Ontario to Midwest just manage distance ahead for safe braking distance . A set of brake shoes is way cheaper than engine repairs, even if they wear sooner.

 

If the overhead is set wrong or becomes out of tolerance it can definitely damage things.

Debris forcibly passing through the nozzles can also cause pressure spikes/load on cups/cam/rockers. That's why i always run much better filtration and just change them sooner.

 

How often do you do overhead on your truck and what it cost you??

 

Me,
100k miles first time
Every 200k after that...
Cost at dealer usually around $800 in Hagerstown MD

No harm in doing sooner though.. especially if you notice anything performance not quite right.