So...whacked a new bargain priced Pipercross hi-flow filter in my new V6, and in doing so, disturbed the obligatory gaffer-taped intake pipe. On closer inspection I discovered it had been (badly) glued together, and was such a mess I gave up trying to bodge it and ordered a new pipe from Mazda. But it hasn't solved the problem.

When I start the car cold it idles at about 2000 revs until warmed up, then the revs continuosly bounce between 1000 an 1500k. A right pain in traffic.

Throttle isn't stuck open, idle hasn't been adjusted. I tried bridging GND and TEN with it running tonight expecting the revs to drop, but they carried on bouncing between 1000 and 1500k. Surely I haven't knackered the MAF by unplugging it and plugging it in again?

Next on the agenda, clean MAF once I have a suitable cleaner.

Any other suggestions? And are BA MAFs the same on all engines?

sounds like a vacuum leak to me

Thanks Brucey, do you mean the little vacuum pipes? I thought it must be sucking air from somewhere, but I can't see anything wrong with them, and I haven't touched them, but I will look again in the morning.

Yes, I've had the same symptoms that you describe and it was drawing air in after the maf. Easy to accidentally knock one off. Also double check the new intake pipe is sealed around the throttle body, there's a little locating notch that must line up to the top of the throttle body. If it doesn't it will hold the hose up a couple of mm

Well, I went over all the connections with a fine toothed comb this morning. Everything prefect. Took out the PCV valve and checked it rattles, then just as I was putting it back, I spied something inside the cam cover. Fished out two large plastic pieces of what looks the remains of a plug boot. My diagnostic skills hadn't accounted for that, lol.

I then bridged TEN and GND and reset the idle and everything is back to normal. The plastic bits were too big to fit through the PCV and get into the throttle body thankfully, but they must have been blocking amy EGR recirculating. I'm not too impressed a previous owner has left them bouncing round the cam cover either Time for a new gasket and proper clean out for the next job I think

Thanks for the help Brucey, thinking it was a vacuum problem put me on the right track

glad you found it