2016 f150 5.0L 170,000kms stalls out or some times idle drops then picks back up. when coming off hi way to red light or stop sign.

Cleaned the throttle body
changed purge solenoid
changed air flow sensor
changed oil pressure sensor
seafoam in gas
Gas storage additive for water in gas

After purge solenoid replaced it seemed to go away, until driving to very low on gas filled up then it came back. Driving home I get off the hi way and first red light i come to it idles low stalls out. restart the engine and and no problems runs fine, l add fuel additive for water in gas then later that week same problem.

any ideas ?Engine stalls

 

All you did was spend money on guessing.
Only one item may be a clue.
That is the Purge Solenoid valve.
If it altered the issue even once, it may point to the Purge system.
Filling up with fuel changes the conditions for Purge.
Any tendency to overfill/cram at the pumps can cause saturation.
It may or may not be in fault.
It has to be tested for function.
Once the filter gets saturated, it needs to be replaced.
If the charcoal filter gets saturated, vacuum may draw fuel out of it, at Idle and cause the stalling from the raw fuel being drawn in at the throttle body.
Just offering a clue.
Good luck.

 

Any error codes?

 

This is the classic VCT solenoid symptom although the other mentioned items can certainly cause this problem. The best way to check out the VCT system is to hook up Forscan & check for any pending codes. Note that pending codes will not always throw a check engine indicator. If you have any VCT pending codes then you need to monitor the associated PID’s to get a better handle on what’s going on. Most of the time it’s just a VCT solenoid that needs replacement – use only the OEM part. You can read about this in more detail here: Idle issue

 

thats roughly 105,000 miles....have you changed your spark plugs?

 

This is very commonly from VCT solenoid issues. Those are generally caused by dirty oil/oil run too long. If you get a code for timing advance/retard try an oil flush and shorten your interval

 

Two different dealers could not find the problem, after several visits
No codes or CEL. As it happens once in a while.
The previous owner did almost no maintenance. I went at it with plugs oil filters clean throttle body purge sol fuel additives, oil flush running hi test gas only.
It seemed to go away until one day i drove it low on gas filled it up then stalls at light after coming of hi way. So thinking water in gas I put in fuel stabilizer and the stalling went away.
Then stalled out one more time. now its back to normal.

Can VCT be intermittent.
Do I have crap in the bottom of the tank.
Is my fuel pump/ filter bad - intermittent ?
It some times stalls Without filling up on gas, then fine the rest of the day.

 

Yes VCT can be intermittent. Problem is you’ve done so many different things these theres just too many variables. Did you ever test the purge valve? I still suggest it’s the oil and lack of regular changes

 

The dealer recommended more frequent oil changes. Sorry did not test the valve. I think there are several factors at play and not just one. can I monitor the CVT valve while driving.

 

How often were you changing oil prior? Not sure what leads you to think multiple issues are to blame, I think you’re overthinking it