[EDIT!!]
Just back from a couple days free…
Thanks a lot for all your help and answers!

Here are the answers to your questions below.
But, first, a few updates:
Re re re rechecked for all vacuum lines = seems good!
Cleaned my IAC and TB with carb cleaner, and mostly the IAC air passage.

==>Car runs smoother, idle now stays @1050-1100 when warm and does not have this floating idle (VIDEO above) anymore!
I have NO CODES, but once engine warm and idling, my BLM is @121 and INTEGRATOR @136, which suggest me, like DRCoolSE mentioned it, that my car runs a little rich. Indeed, that’s maybe the cause…?

EDIT: just found this on the forum, on why a Fiero can run rich:
"If you turn the key on engine off and the pressure drops then its either a leaking injector or a faulty pressure regulator"

==> Indeed, noticed yesterday that when I turn the ignition ON, the pressure is @40psi, but it does drop!!

If I'm good by narrowing the problem, my 1100 idle may be caused by a engine running too rich, due to a leaking injector?

quote Originally posted by RWDPLZ: Have you replaced the vacuum lines and hoses yet? If it has cruise control, try removing and plugging those lines. Fuel pressure? Last time filter was replaced?

Vacuum lines hadn’t been replaced. Check for cracks and leaks… they seem OK!
Fuel pressure good @40psi at start. Changed fuel pump, filter, lines this year.

quote Originally posted by Patrick: Poor grounds?

Already added an additionnal ground strap coming form the battery to the chassis, then to the engine.

quote Originally posted by 2.5: Does it change at all, get worse when you turn things on? For instance rad fan, ac, blower fan, lights... Have a non stock stereo?

It does not change when I turn accessories on!

quote Originally posted by DrCool86SE: Pretty certain it's the solenoid. So I'm not stressing on that. How are your plugs and wires? Also, is it running rich? Seems like that could just cause it to run a little faster at idle but I'm not an expert....just hypothesizing.

Plugs and wires are new, replaced this year.
As mentionned previously, BLM @128 and it runs a little too rich I think..

What do you guys think?
Thanks again!!

------------------
Christophe
1969 Oldsmobile Cutlass Supreme 350ci - AT
1986 Pontiac Fiero - V6 2.8l - 4 Spd Man
Eibach lowered / Stainless perf Exhaust

[This message has been edited by DJWINNI (edited 11-02-2016).]

[This message has been edited by Patrick (edited 11-03-2016).]

quote Originally posted by Patrick: Without knowing how long it takes to drop to what pressure... that doesn't tell us much! Does it drop to 30psi in half an hour? Does it drop to 0psi in five seconds?

Sorry Patrick!!
40 to 0 Psi in less than 10 seconds!
Does that help?

[This message has been edited by DJWINNI (edited 11-03-2016).]

[This message has been edited by Gall757 (edited 11-03-2016).]

quote Originally posted by Gall757: Yes!..... You are leaking fuel. Either the injectors or the regulator....or both. You should maintain the pressure for 2 minutes or so.

If it was the regulator valve, wouldn't I have fuel smells and leaking on the fuel rail?
As I've none of these symptoms, I'd rather think of an injector...?
Thanks!

[This message has been edited by DJWINNI (edited 11-03-2016).]

[This message has been edited by Gall757 (edited 11-03-2016).]

Will do a leak test next week!
That being said... do you effectively think that this may be a cause for my idle?
Thanks again for all your help!!!

[This message has been edited by DJWINNI (edited 11-03-2016).]