inlovewithavdub

Greetings Honda Lovers, thanks for taking the time to help out this n00b1e.

I've been working on a total swap and rebuild of a '91 VW Cabriolet, so I'm not completely incompetent when it comes to engines, but I'm a newcomer to Japanese autos. I ended up getting this Honda from my sister who rarely drove it and got fed up with this pesky problem. The car has 380-something K on the odometer, but legend has it that the engine was swapped at one point, so who knows what condition ANYTHING is in on this Honda.

91% of the time, she runs like a dream. Does 100mph on the freeway quietly and without breaking a sweat. Every once in a while though, it starts losing power. The cause? Who knows?

Sometimes, it starts and runs fine for days on end.
Sometimes it shuts itself off when I'm idling at a red light.
Sometimes it takes a poop when I change gears, I shift up and hit the gas but it dies instead
Sometimes it sputters or cuts out a little when I'm at freeway speed, then I put it in neutral and rev the engine for a sec and it runs fine again.
Sometimes it just won't start.
20 minutes later, it will start. Or maybe 2 days later. She's a fickle mistress.

Apparently this problem didn't arise until a mechanic installed a new o2 sensor. Might be a red herring, but there's that.

When it dies, there's a faint electrical click as the engine shuts off and the oil pump and battery lights come on.
Just today, the check engine light came on and has stayed on, even while it seems to be running normally.

Sometimes when I try starting it, there's just a rapid click from the starter but it won't turn over.
Sometimes, it starts up but then stalls out again once you start creeping forward.
A couple of times when trying to turn it over, it has made a SERIOUS bad noise like possibly the sound of valves hitting pistons. But then if you can pump the gas enough to get it to turn over, it will purr like a kitten, with no weird grinds or clicks or anything to really suggest that the timing is off.
Sometimes, it doesn't seem to start, but when you turn the key to the "off" position, the car shakes a little as though to suggest the engine WAS running, just at an extremely low RPM. Might also explain why the starter sometimes makes that grinding noise.

The mechanic's diagnosis? Needs a new battery. The battery was indeed looking decrepit, so I replaced the battery, it ran great for 3 or 4 days, then the problem came back. Also, "jumping" the car when it's in "no-start" mode doesn't ever seem to fix the problem. Prayer beads seem to have more effect than jumper cables do.

My gut: Fuel delivery problem. Filter may need replacing. (Any suggestions on how to go about, removing the thing? Yikes, it's in there tight.

Also possible: Aging spark plugs. Faulty idle control valve. Lousy fuel pump. Fuel relay or other weird electrical BS. Perhaps some previous mechanic forgot a ground wire. Timing belt may have slipped or is just getting old. Clutch or transmission may need service. Possible gremlin infestation.

So yeah, basically I'm stumped. Any ideas? This a common problem or possibly a recall? Your imput is very much appreciated.