English isn't my native language, when you mention that you had a tune-up, did you also replace new plugs, cap and rotor? And I would certainly check for vacuum leaks (see youtube clip below).

More likely the fuel pump or fuel pump relay than injectors. Get a cheap tire gauge (will be destroyed unless you have a fuel pressure gauge) and check fuel pressure at the schrader valve after prime (before start), then at idle and report back.

Cleaned MAF sensor. Working on fuel filter now. Cleaning the MAF does nothing about 99% (99.9% ?) of the time, unless the sensor surface is visibly oily or dirty. If you want to investigate the MAF, unplug it before you start the car, then run it for a while with no MAF. The car will use default ai...

It sounds like the engine runs OK when at higher RPM and not under a heavy load, but it doesn't idle smoothly or run smoothly when under load. Does that sound about right? There could be more than one cause of the symptoms. I agree with the above suggestions to check the fuel pressure (to address th...

One other thing to check is the condition and tightness of the hoses to and from the intercooler. The car runs much as you describe if there is a loose hose or a hole in one of the hoses. The holes usually occur on the side of the hose where you can't see it without removing the hose from its connec...

Step back a bit and think basics and don't get lost in the possibilities. After warming, unplug each wire from it's designated spark plug and listen for arcing, see if car runs obviously on one less cylinder. You may have done this. Then as suggested in other posts go directly to compression test. B...