I occasionally get P0507-001 code. I think I m going to replace the TB.The A/C on and being in gear put a load on the engine. In order to keep the RPMs the same, the ECU needs to open the throttle more to compensate for the increased load. That effectively reduces the vacuum created by pistons. You can watch the gauge move about 5inhg when parked and the a/c running when the compressor engages and disengages. Same when parked and the SAIP cycles.
Well, i prepared the engine for compression test.I wouldn't consider replacing the throttle body without checking a few things first.
I suggest you check each cylinder compression. Have you done this yet ?
Spraying brake cleaning fluid on the vac lines won't detect an internal leak such as a faulty PCV valve or suction jet pump.
Thanks."With headlights on, turn the key, lights go off and come back when I turn the key off."
That is normal.
The compression is fine on all cylinders.
Have you fixed the no crank problem ?