ok so in the 94 i just bought, i tihnk there is a vaccum leak somewhere in the blend door system, check this out, with moderate/hevay acceleration you can feel the misfire AND the vents will default to the defog position, so my question tho, could a vaccum leak in those bitty vac lines cause a misfire?

Wow, Vacume leak????, does it do it with the venting turned off, i.e everthing turned off, fan to off, vents set to cold, and climate set to off.??

Is there an aftermarket stereo in it???.. If so the climate control cluster is right above, maybe when they installed it maybe one of those small vacume lines got pinched or cut???.

If not, it'* easy to check!. Your fake wood paneling that runs around the radio and over the steering wheel to the left side will pop off with a little force ( there are just metal clips holding into place.) Then there are a couple of screws that hold that insturment cluster in the dash, and while your at it, unscrew and pull out the radio for a little eye room and see if there is anything not hooked up to the climate control, or like I said pinched hoses? cut hoses or maybe even not hooked up?.

Are you talking about a shift in the A/C vents. I had these issues. For me there was a junction under the dash that had vacuum lines that got clogged. I took out the junction and connected it with vacuum hose and fixed the problem..

A vacuum leak won't do anything at heavy throttle position because the engine isn't making any vacuum, so your misfire is probably from something else.

You might want to check the vacuum canister that "stores" vacuum for when your on the throttle hard and there is no vacuum for the vents. A chack valve might be bad, cuz I know when you loose vacuum, it defalts to defrost as a safety so you're not forced to usa a towel to defrost you windshield. You migh also have a leaky vacuum actuator that causes the canister to loose all vacuum.

Good luck finding the problem. I hate vacuum leaks.

Of course, I overlook your question and make up my own.

No, a leak in those lines will only cause problems with idle quality and won't effect moderate to full throttle opperation.

Hang in there guys...

Nerv...there'* a couple things here. First off. The vacuum for your door selection comes from the engine to a vacuum canister that is mounted next to your window wiper motor on the firewall in your 94. (96+ models have the cruise control there and the canister is under the passenger front fender). 99% of the time when you punch it and the air moves it is due to a old or loose vacuum hose going to the canister.

As for the misfire. Check that the #6 plug wire isn't touching the O2 sensor or wiring. Ohm meter the coil packs and check the condition of the plugs/wires. This seems like an ignition type problem, not vac related.