OK, here's the story,

Factory rebuilt, normal ported engine with about 625 on it, and turbos with about 9,000 on them. Started up fine (normal 2.5-3k spike, then to idle,) ran fine, normal spooling response (10-8-10,) until I got off the freeway. Then the car started having power surges. It would bounce between 1.5-3k while at a stop. Pulling about -20 on the vacuum at the same time. What blew off/got stuck/broke?

 

Mine does it too. Sometimes right at start up. I somehow got stuck with a paper intake manifold gasket on my mana motor. I need to get the metal gaskets mazda uses now. I know its leaking.

 

I know I have the metal gaskets, I saw them on the block. I have done some research, and there are two possibilities.

1. A stuck double throtle valve, or problems with the vacuum system for it. Pop the elbow, and lube/clean the apparatus.

2. Hose popping off the EGR valve. This means taking of the crossover tube, some other hoses, and manipulating the hose with a pair of hemostats (it's great to have access to medical stufff

I will let you know when I get it home to tinker with it.

 

Well, checked the throttle body, and it was clean. I never managed to get to the EGR system. But somehow, some way, it corrected itself! This leads me to belive that it was a stuck EGR valve that got stuck when I went through the initial turbo warmup (10-8-10 in third gear.) I was going to take a huge (60cc) syringe, pull of the vacuum hose running the bloody thing, and gently persuade it with air. It took some driving in the driver friendly DC beltway (riiiiight!) to knock it back into operation. I would still replace the EGR, but:

1. It can wait until after I am done with my next business trip.

2. It is not an emergency replacement now.