Engine seems to misfire at 2K

[Tim OLeary]

So after struggling with the rough engine issue, I found that using hi test clears up the issue. Does that point to a defective component?
TIA

 

[Tim OLeary]

Is there a reason my truck runs better on hi test? Is using regular with an additive a more economical alternative?
Thanks!

 

[DILLARD000]

Year Engin Trans 2WD\4WD ? Basic vehicle info in your avatar+profile+threads encourages a response.
Assuming a V6~4.0L~SOHC? Might be any of several things:
* KnockSensor Bad\Intermitent\BrokenWire; PCM uses this to adjust timing for LowOctaneFuel.
* FuelSystemCleaner\SeaFoam & a PremiumFillUp once a year is a good practice.
How many Miles\Yrs since:
* Renewing Plugs+Wires+OxSensors+FuelFilter, Cleaning+Testing CoilPack; needed every 100kMiles\12Yrs?
* Cleaning MAFSensor+Throttle+IACValve+Intake+EGRValve+DPFETube; needed every 33kMiles\4Yrs?
* Cleaning\Renewing PCVValve, Inspect PCVHoses for Cracks\Leaks; needed every 33kMiles\4Yrs?
* Cleaning AirFilterBox, Renewing\Cleaning AirFilter; needed every 8kMiles\1Yr?

 

[Tim OLeary]

We've done these things, and also a very skilled mechanic also analyzed it.
The knock sensor is something new to me until recently when I put my Bluetooth module on our 2004 TAHOE to analyze a "Check Engine". It reported a problem with the knock sensor, which after I cleared it hasn't returned, and the TAHOE runs smoothly. And the ST never showed the knock sensor trouble code.
Thanks!

 

[DILLARD000]

Compression test?
A bad FuelInjector?

 

[Phil Frady]

I would say dirty injector(s) but not dirty enough to give you a lean mixture code. Maybe a fuel filter?

 

[Tim OLeary]

Thanks for the ideas