@Xulfiqar, cleaned the intercooler out and straightened the fins as much as I could . Took about an hour, minimal oil residue inside.
Also changed the valve cover bolt washers that were completely worn out and leaking oil all over, cost Rs. 150 for 4 pc. "Cultus ke tappet cover ke washer."
Noticed that the exhaust manifold bolts are done for, as is the EGR hard line. I'm going to take the time out to have the heat shield, exhaust manifold bolts replaced and the EGR line either blocked off or cleaned out.
Will also check how bad the turbo is, since it's been whistling and chirping between 0-2 psi for a while now. Maybe it's gaskets, maybe it's play so bad the entire turbine that needs replacement.
Driving on the higher boost has resulted in my fuel consumption being 7km/L and 7.07km/L for the last two fillups. This is within margin of error of my lifetime 6.66km/L average.
I've just moved to colder plugs from NGK 6 Platinum to Denso 24 Iridium (NGK 8.) The NGK plugs had only 7300km on them, but they were absolutely dry fouled - confirming how rich the fueling is.
On the old plugs, the engine would gently misfire consistently when idling cold, and would hesitate with a loss of power if <2500rpm and >7psi boost. If I didn't back off the throttle and reduce boost at this point, I could hear pops and crackles, which I'm guessing was detonation.
Per Denso, plugs of this type with heat range 24 and over have a +0.5mm spark position over the 1.0mm position on plugs with a <24 rating.
Update: The cracks and pops and loss of power is WORSE with colder plugs, AC and headlights on!
Higher impedance? Nothing to do with the plugs at all, and rather ignition coil and alternator?
Idle volts (at the 12V socket, so voltage drop etc.):
13.7V no accessories
13.2V blower fan 2
12.7V AC on, blower fan 2
11.4V AC on, headlights on
I think it's this damn alternator causing ignition voltage to be below what's required. And/or:
* wire impedance
* plug impedance
* worn ignition coil
I'll try switching to the absolute cheapest copper Denso 16 plug until I find another alternator.
I need an actual mechanic, man.
Here's a video of what's happening: https://streamable.com/usmh6d
The hotter NGK 6 plugs did this too, but much less often than these new Denso 24 plugs do. I can't accelerate anywhere near as quickly as I could before.