2008 Impreza stalling issue

[Mikesaj]

Hey everyone. New to the forum and new to Subarus. Bought my first one a couple days ago.

It’s a 2008 Impreza 2.5i 5 speed manual. 250k km (155k miles)

It runs and drives perfectly fine for the first 20 minutes or so. Any longer and when I come to an idle it stalls. It drives perfectly otherwise. I can drive on the highway for an hour just fine but when I slow down and come to an idle it’ll stall. If I push the clutch in and let the rpm drop it’ll stall. If I have press the gas at all then it stays running just fine. No chugging or misfires. As soon as the rpm drop down to idle it chugs and then stalls.

So far I’ve cleaned the throttle body and the maf sensor.
Checked the fuel pressure it’s at 40psi in run position 55 psi when running drops back to 40 when the car dies and does fluctuate at all.
No codes coming up either

If I red line it then a bit of blue smoke comes out the exhaust. None out of the oil fill cap and oil is not milky

What should I do next?

Thank you

 

[p0mar]

Is it completely stock? I’ve heard of this happening where it’ll stall while idling or if put in neutral but still moving and the rpm drop to 0, it can be due to it having some mods and it not being tuned even if it’s just an intake or certain exhausts.

 

[Mikesaj]

Turned out to be spark plugs. The plugs were fouled with oil. Changed plugs wires and ignition coil about 1000 ago been running good since