00 Miata idle problems. Only at speed. Need help ASAP!

[Meat Ball]

Hey everyone. I'm sure this has been posted up plenty of times but I've reached a dead end with Ideas.
Some serious input would be appreciated. I've had nothing but headaches with this car since I've bought it.

Ok, as for the symptoms. I'm getting a crazy misfire around 3,500 RPM-4,000. (mainly in 1st gear or at 6th) The car feels like it loses power/bucks, then it's fine. Other times it's a lot more severe where the RPM drops at below 2,000. It's managed to shut of on me once before on the Fwy. (Not fun FYI) Then I restarted the car 15 mins later with no problem. WTF!?

So far I've replaced the TB (doe to slipping), accessory belt, Fuel pump, Fuel filter, Plugs, NGK wires, Cam shaft sensor, Crank shaft sensor. All these parts have literally been changed out for about 3k. Now I'm getting 2 codes #P1141 & P1345. I've heard P1141 can mean a bad "MAF sensor"? or rear O2 sensor? But as for the P1345 going bad how is that possible. (Premature failure?) I just change it out about a month ago? FRAACK!

Yes, I have cleaned my EGR and it did make a difference for a few days then the CEL and misfire/bucking came back. :fp:
If you guys could point me in the right direction or have any clue I would be very grateful and happy.

Thanks,
A frustrated NB owner!

[Meat Ball]

Any input gents? I'm tempted to soak my EGR in gas overnight to see if that cleans it any better then the 1st time. Also just changing the rear O2 sensor.

[kung fu jesus]

Have you cleared the codes after making the repairs?

If you have the means, try to borrow a MAF from another car, reset, see if that helps.

Try tracing your wiring on your sensors back to the ECU. If someone, like the previous owner, was in the wiring to add something for an FI system, they may have done some shoddy repair work when it was removed.

Just briefly looking, there is some good info on this external thread:
http://forum.miata.net/vb/showthread.php?t=463217

[Meat Ball]

Thanks for the info Kung Fu Jesus. :)
I did manage to clean my Cam angle sensor & Camshaft sensor. Also relocated the little nipple sensor that's connected to the MAF on my short ram intake.
Forgive me for not knowing what it's specifically called.:fp:

Anywho... I drove the car fairly spirited with not misfires or hiccups.
I also did notice the CEL went off.
So I'm pretty content for the time being.

[SM16RMSM]

I did some readin on the codes. P1141 is basically telling you "HO2S Bank 1 Sensor 2 Heater Circuit Low Input" meaning the rear O2 is bad. There is a heating element built inside the sensor itself and it has quit working. The P1345 is related to the Cam or Crank position sensors. It means that it not picking up a signal which could be why the NB not running correctly. If it starts to act up, use some electrical cleaner and clean the connections between the plugs. Also, make sure you gap the crank sensor correctly. If it too far away, it won't read and lead to a misfire or loss of power.

[Meat Ball]

Thanks for the input. I'll try picking up some electrical cleaner this weekend and give it a shot.
From what I remember reading, for the Crank shaft sensor the gap needs to be about a "credit cards" width. Right?

[Meat Ball]

After cleaning out all my lines and relocating the MAF sensor bung. The car is running 100x better.

Thank for all the help Gents!