PCM is the actual name for it. It'* the computer. Above your front passenger'* feet, below the glovebox. Silver box. The main brain.

Ok, then i know.
Just didnīt recognize ECU, have only seen PCM and ECM before.

/Mikael

A bad ECU (ECM PCM, whatever you want to call it) can be hard to diagnose, but cause all sorts of wierd problems. Sometimes, it'* easiest to diagnose by swapping a known good unit in and see what happens.

It is under the passenger side of the dash. You have to remove the black kick panel from above the passenger foot well to get to it. You'll have to lay upside down to see it. It has three connectors on it, and is held up by one metal tab and a bolt, then you have to wiggle it at just the right angle to get it out. In my opinion, it'* worth a try. But don't pay for one before testing unless you are sure you can return it.

i have seen maybe mechanics Diagnose the PCM as being bad and they were wrong personally i would resort to that last because PCM'* arent cheap at all and if your wrong thats a big Opps

This may not apply but as with the other power systems (battery, alternator) make sure they have good connections. Our Caddillac was misfiring and was throwing out all kinds of random codes every once in a while like power steerling loss because the battery cables was loose and was confusing the PCM. After tightening all the problems went away.

Now I have checked alot of connections and cleaned them.
Yesterday I took the car for a ride, went better than before and when I came back the "Service Engine Soon" lamp went away.
Then I cleared the codes, and left i until today.
This morning I went out and started it up, misfiring again :(
This time it missfires when I give a little throttle, nothing in idle though idle is a little to high.
When open up the throttle moore it comes to a limit where everything seems to work again, so at high revs there doesnīt seem to be a problem.

Really want all help I can get!

/Mikael