elimnate the simple stuff - is the coolant level ok? and i mean
checking inside the rad, not looking at the level of the expansion
bottle. if the level is not high enough, the engine can get a false
"cool" signal on the head temp sensor. the ecu then injects too much
gas, and when the engine is hot, it will randomly misfire. i had a
civic with this problem and did pretty much all that you did before i
figured it out. _never_ trust the level in the expansion bottle. if
there's the smallest air leak in the coolant system, when the engine
cools, it sucks air back through the leak rather than refills from the
expansion bottle, so the coolant can be significantly low without it
being obvious.

airboatman wrote:
> I have a honda accord lx 4cyl vtec that has 70k miles. It is missing
> pretty bad. The check engine light is on and flashing sometimes. The
> codes set are 71 (random misfire) and sometimes 72,73,74. I suspected
> ignition so changed in sequence the coil, rotor, distributor cap, plug
> wires, plugs, ICM and then the distributor assembly (with cam position
> sensor) none of the changes made any difference. I have also checked
> valve adjustment, compression and pinched the return fuel line and
> listened for changes. I have listened to the injectors with
> stethescope and they are consistent. I pulled the fuel pump from the
> tank and checked for screen clogged etc. None of the above has led
> anywhere. I don't know what to try next. Help!