Hi, This is a tough one. I just bought an '88 535i 5-speed and it has these intermittent problems that I'm about pulling my hair out over. I listed the issues below, along with what I've tried so far. I've tried to be methodical. If anyone is willing, please read this through and offer some suggestions. Also, if you will, notice what I've already done before suggesting ideas. I think I've hit most of the biggies. I need some methodical way of debugging this rather than a "replace the _____ I did this and mine worked" approach, if you know what I mean. Thanks a bunch, everyone! Problem(s): Engine cuts out intermittently - When it does this, there is an immediate, sudden drop in engine power (the car bucks), the MPG gauge on the dash swings to the far left and sometimes the tack jumps to the left. This happens randomly, sometimes as few as 5 times a day, but most often within the first 20 minutes of running the car. It lasts about ÃƒÆ’Ã†â€™ÃƒÂ¢Ã¢â€šÂ¬Ã…Â¡ÃƒÆ’Ã¢â‚¬Å¡Ãƒâ€šÃ‚Â¼ second then the car runs normally. It can happen any time during the day. When it's doing this, I can feel the Fuel Pump relay clicking if I put my fingers on it. So it's like the ECU is telling the thing to drop out. Along with this, when the car is started from dead cold in the morning, it runs fine (except for a few cut-outs described above), then at about 4 minutes 20 seconds the car begins misfiring badly and loosing power. After about 1-2 minutes of this it evens out and is fine for the rest of the day. Note: After exhibiting the problem in the morning, the car will often run fine the rest of the day even after sitting 9 hours on a work day. I talked with the previous owner and confirmed it's been doing this for years. (This seems to not be moisture related because I drove home from work after the car sat in the pouring rain all day and never had a problem.) When running normally, I think the car is running rich, but other than that the engine is smooth and quiet and has good power. Revs up nicely, sounds solid and smooth. When it runs, it runs very nicely. What I've tried with no effect to the problems: - bypassed the main relay with jumper. - bypassed fuel pump relay with jumper. - run with O2 sensor unplugged. - run with Throttle Position Sensor disconnected. - bypassed CODE relay (in OBC relay box). - cleaned and re-seated every connector on the fuel injection wire harness (inside engine bay and under dash near ECU). - cleaned every ground connection in engine bay and under dash (not in trunk, though) and applied contact cleaner, then electrical grease. - wiggled every wire I could find under the dash, wiggled every wire and connector I could find under the hood. Parts replaced or tried with no effect: - crank position sensor and speed sensor on the flywheel - new - fuel filter - new - fuel pump relay - new - coolant temp sensor - new - spark plugs - new - plug wires, rotor and cap - new - thermo time switch - swapped with used - Air Flow Meter - swapped with used - Motronic unit - swapped with used - Vacuum hoses (small ones) - new - Intake boot - replaced with known good used - Ignition coil - previous owner swapped with used I thought next I'd try ohming out the fuel injection wire harness. The other thing would be to bypass both the Fuel Pump and Main relays. I've bypassed each individually so I know it's not the relays OR control to the relays that's causing these issues. Other more "shot-gun" things are to swap the ICV, sap instrument cluster and a different AFM. As an asside -- does anyone have a known good fuel injection wire harness they'd sell REALLy cheap? Or maybe let me try out, or be willing to trade for something? Thanks! Mark.