I have a 2008 Isuzu ascender with the 4.2L.
ive rebuilt the engine with pretty much all new stuff.
The vehicle idles beautifully when you first start it but once you drive it around for a bit it starts to run rough at lights, shuts off sometimes when you slow down or make a hard turn.

Ive replaced:
Cam sensor
crank sensor
Exhaust cam actuator
Exhaust cam solenoid
Spark plugs
Crank Shaft
Connecting rods
Rod bearings,
Main bearing w/ Thrush bearing
Timing chain w/ guides and tensioner
from oil pump repair kit
to all new gaskets and head bolts.
From a good engine clean to a
Clean throttle body

I pretty much gave up on it and took it to the dealer,
They told me everything is fine, i told them to take it on a test drive (which they did)
Then i get a call about it being an intermittent problem and they cant really pin point the issue..
they said maybe Cam Actuator Solenoid wire.
by the way STILL COST ME $120 for diagnostics.
I replaced a pig tail all the way to the pcm.
Still the same issue.
any help guys??

Also it will hold a bad idle till i rev the engine, then it will smooth out again.

 

Update:
I drove the vehicle over the weekend and it stalled a few times,
but when it was at higher speeds the truck drove perfect.
its starting to seem like it cant find its idle at low speeds or going to a stop.

Here are some of the DTC codes that are popping up.
P0017
P0014
P0106

When i flash the codes they do not appear on my scanner under
"Pending codes" till i start to have a low idle problems.
but the idle doesnt give me a problem all the time.

 

So this week i became so frustrated i just pulled the
intake off, valve cover, oil pan down, dropped the pick up tube just enough,
The radiator, hermonic ballancer, and removed the front cover too find my
New in the box Chain kit have been stretched out.
a majorly stretched chain from the factory could of caused my whole
headache.
This morning my replacement chain will be on and i will give everyone a heads up on the progress.