Thanks donbrew. Will do that and post the results! :)

 

OK. FYI Auto Zone "rents" the pressure gauge kit out for a $150 deposit which they refund upon return. However this results in a $10 state tax so basically $10 to rent the kit for up to 30 days. Not too bad.
Anyhow, fuel system primes up to 55 lbs. With engine running at idle the gauge shows 55 lbs with just a slight variation. Holds solid at 55 lbs when keyed off. Holding solid at 10 lbs after 5 minutes. However, all this was done while the problem was not manifesting so I will hold onto the kit and when the problem shows itself again will check the pressure again. The other day when I did the videos the problem was fairly consistency happening. Today..no.

 

I don't know how Massachusetts operates, but the tax should be refunded also.

 

Update: Had the fuel pressure gauge hooked up and voltmeter monitoring the battery and the engine problem manifested itself on numerous successive starts. The fuel pressure held solid at 55+ lbs and the voltage only varied according to the rough low idle. In fact, this time the engine actually rough idled to a stall multiple times. So a trip to Auto Zone to return the pressure gauge is next and then a trip to my local mechanic to see if he can read any pending codes. More to come....

 

I know this is a shot in the dark.
First off might have missed how many miles on the car.
Have you ever cleaned the Throttle Body and Mass Air Flow sensor ?

 

Hi and thanks for the suggestion. Mileage 83,303 miles. Yes, I cleaned the MAF sensor with the correct cleaning fluid and also the Throttle Body plate.
In talking to my local mechanic just now, he tells me he can't read any codes with his equipment unless there is a Check Engine Light which there is not. On the phone he mentioned the possibility of a bad MAF or Idle Air Control valve. Well in reading here it seems that there is not an Idle Air Control valve on these engines (LT with 2.4L) so while I returned the fuel pressure gauge to Auto Zone I picked up a new MAF on the off chance that mine is intermittent and perhaps soon to fail. After installation the engine starts fine and runs as it should. Will see over the next few days if this has eliminated the rough idle on startup which was sort of random but frequent. Will report back here after I get the chance to check it over a few days or a week or two.

 

Ah, a bad MAF, plausible, some PO might have tried to clean it with the incorrect spray.

 

New MAF...alas, still same problem after $70 investment! Now thinking small vacuum leak somewhere on the intake system. Will ask my local expert tomorrow.
BTW, i am trying to get the Check Engine Light to activate by leaving the gas cap off but so far after 5+ miles of driving around it has not lighted :)
Hmmmmm.....

 

OK. My local and very trustworthy auto technician/mechanic tells me the probable source of my problem is the actual throttle body. As it does not have and Idle Air Control unit the unfortunate news is the whole TB would need replacement. He advises me to drive until it throws a CEL code unless it gets to be too much of a problem before that happens. So now, in preparation for an eventual TB replacement, I wonder if there is any such thing as a re-manufactured TB for my car or what experiences folks here have had with used ones from a junk yard? He did tell me it would need to be programmed by a dealer but that he could do the install when I am ready. Advice?

 

Any chance this is more likely when the car hasn’t been driven in a few days? That this is your dinghy-towing ride suggests it’s not a daily driver. Winter and an even slightly run-down battery virtually assures sulfating, and then it won’t hold a full charge. If it’s just one cell the voltage will drop to 10.5-11 volts which might start the car but the electronics go bonkers. Maybe when the the voltage comes up the problems abate. Maybe not.

Load testing at the parts store doesn’t detect this problem.

This forum has taught me what I should have already known; don’t bother doing anything else until you prove you have a good battery and that it’s getting fully charged and staying that way. Usually something to that effect will be one of the first comments here. Did I miss something?

You could let the car sit for a week and then check the battery voltage before turning the key.

Just today on one of the Facebook pages a guy had an AC Delco battery (less that 3years old maybe) replaced free under warrantee for the exact problem described above. It solved his mystery problems.

Still fun learning something by reading about all the other possibilities tho...