Hmmm... Sounds too simple to be true, I'm not that lucky! How do I verify it?
I'll start with replacing the throttle positioning and be back with an update.
Anyway, tonight I tried to recreate the problem, in every and any possible way. Stop, slow acceleration, stop and floor it, stop and go etc. Nothing. Not a single glitch or hesitation in 20 min... Hope it won't die on me in Georgia mountains downhill during my vacation...
I would do an electric test before any long trip. As below.
Battery cable/wiring check
This should take about 5-10 minutes.
Tools. Digital VM, range 200MV to 2.0V.
- Key on (not start) Blower on high, lights high beam.
- Probe leads, Pos battery post to mega fuse (or older cars use post on fuse box) Not the cable ends, but, post to post to bridge the cable.
- Volts range ~100 mv or less. ( 0.10V or less)
- Neg bat post to engine metal 50 mv or less.
- Neg bat post to body metal 100 mv or less.
On the pos side, high reading = bad cable, or ends not good connection.
On the body ground (fender) high reading = bad cable or ends not good connection.
If you have a high number, then measure one step at a time; that is post to clamp, clamp to wire, wire to eyelet, eyelet to fender etc. Find the weak connection, and fix it.
On the negative side, the ground is split with one to the body, one to the engine block and then the ground strap from the block to the body near the passenger side firewall. Thus the body is double grounded. You need both. Engine strap to firewall is important as this is the ground to the PCM
Ground strap test. Key off . Remove the battery ground to the fender from the fender. Turn HL on high beam. They should light normal. If not the ground strap from the block to the firewall/PCM post is bad. Clean the fender where the neg cable bolts on, put the ground cable back. Fix the ground strap. The ground strap keeps the PCM
and engine block/Alt at the same ground level. When the engine is running, the negative current path is mostly engine block-ground strap to the body, bat cable to fender is secondary.
Alternate test of ground strap: HL high, blower max, start engine and idle in N.
Test volts engine block or Alt to the body common post for the ground strap/PCM. Max 75 mv.