Thread: 3.9 cutting out

I would consider checking your fuel filters. and vacuum lines

For a diagnosis of what is stopping, try connecting 2 wires to the ignition coil, one to the positive terminal and one to the negative. Bring these inside the car, fit a small light bulb or preferably a LED tester to each wire and earth the lights. +12V wired light should stay on steady. If it goes off while driving look at your ignition switch and your immobiliser circuits. The coil can be hotwired from the ignition switch direct if needed. Negative coil wired light should flicker with engine ignition. If it suddenly goes steady when the engine dies look at the ignition amplifier and reluctor pickup inside the dissy. If the ignition stays normal when the engine dies connect the test light to the fuel pump circuit and the injector signal. The ECU gets its RPM input from the negative side of the coil, a white/black stripe wire. Check all connections in this area.

Knowing what is dying is invaluable. A 12V switch with an internal LED can easily be used as a test light (and switched off when not needed). I did this recently on a Nissan Skyline and it was invaluable in narrowing down the area of trouble.