Still running rough

[Frederick]

To elaborate on what Don has above....
Vacuum leaks (unmetered air entering the intake system) can be a real problem.
By spraying around areas that may be leaking - you are interrupting the possible inflow of air by sucking in a bit of 'fuel' instead.
The engine then (momentarily) runs different (usually better) and you get feedback on where the problem area is.
This method also works on carb engines also (including seeing if the throttle shafts leak or carb base is warped/gapped - each allowing in air).

Just love how SFDON’s criptic advise gets explained by other members. Cracks me up.

 

[Henrik]

Just a tip from Dr. Djet regarding a similar case:
"Excessive air would increase engine rpm. As you were talking of a sweep in idle-run rpm, that was my hint. Sometimes you have a leakage that just happens at certain temperatures. It can even be the shaft bearings on throttle valve or the rubber sealings under injectors."

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[Frederick]

This issue is discussed by Steve Nelson at Top-end Performance under his article dealing with installation of dual side draft webers as well as triples or any carbs.
Says that vacuum leaks are the single most common cause of weber’s not running properly . he recommends starting fluid or ether. It worked for me.