97 impreza sti.the codes are working i disconnected maf to see if it made a difference it didnt checked codes and it showed 23 ie maf sensor but thats because i disconnected it.cleared codes checked again showed no faults

have a repair shop check out the MAF sensor signal. If they determine that its bad, get them to replace it. If that doesn't fix it, then its their problem, not yours. If you buy one and install it, and it doesn't fix it, your not getting your money back.

Here is a list of Subaru diagnosis codes. If these are not what you are coming up with let me know the numbers you are getting and I will look them up on my genisys scanner to further assist you.
1111 No codes stored
11 Crankshaft position sensor (Don't confuse with above, usually when the crankshaft sensor if dodgy the thing won't start anyway)
12 Starter switch faulty
13 Camshaft position sensor
14 Injector no.1
15 Injector no.2
16 Injector no.3
17 Injector No.4
21 Engine temp sensor
22 Knock sensor
23 Mass air flow sensor
24 Idle air control sensor (usually accompanied by running too fast/slow)
31 Throttle position sensor
32 O2 sensor
33 Vehicle speed sensor
35 Emissions canister purge valve
38 Torque control signal (Automatics)
42 Closed throttle position
44 Turbo wastegate regulator malfunction
45 MAP sensor
49 CO adjustment resistor for older cars not fitted with cats
51 Neutral switch (Manual gearbox)

The p1140/121 code indicates the MAF was not as expected compared with values from IAT, TPS, CTS, IAC command, and RPM. Meaning all THOSE sensors and the IAC solenoid position data have to be working and in normal range for the MAF to test normal and not code. Further, any vacuum leaks will ruin the MAFs accuracy when compared to the others, as will a PCV/CCV problem.
If you lobbed a MAF at it already...you have already done the least likely and most expensive part. You really need to look at data and see what the DME sees. Is throttle showing closed at idle, is air temp normal? Is RPM under 725 idling, does it flare idle up and down in 10 seconds. is there any vacuum leakage anywhere? even a small amount can make a code level of difference?. Intakes leak a fair amount. CCV valves much more likely to leak, as are the hoses to it. TPSs dont fail that often but can. IACs usually code when they fail...but they could plug up and not code but have improper air bypass that affects the MAF reading. Throttle cables/adjustment is critical...keep that high on priority list.
iATN Tech.

the sensor that controls the mixture is the heated oxygen sensor in the exhaust manifold before the cat converter
if that is the one you disconnected and it made no difference then logically if it was working ok then there would have been a difference
replace it and see if there is a difference

Check the flexible air inlet tube.

Make sure it's 100% seal between the air filter to the intake manifold on the engine block.

Air rushing into the intake (after Mass Air Flow sensor MAF) will lean out the fuel mixture.

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Clean and inspect for other air leaks on vacuum hoses and intake manifold gaskets.

Defective MAP sensor can also cause similar problem.

hi that sounds like the idle control sensor or tps throttle position sensor, if the i.c.s is stuffed you wont be able to boost and ur revs will be all over the show going up andown when car isnt moving hope this helps5

are you sure you do not have a wrx-sti??? an H7 is the low beam bulb for a non sti......an sti has a different bulb. D2S. HID lighting.

can any1 help me as my interior light not workin with doors when i use door settings get nothing till i close the doors and it comes on dull

if your run no air sensor it wont rev past 3500rpm as it would not richn the engine under load

replace fuel filter