rough/surging idle in drive/reverse only......gotten worse....please help

[spunger]

Well it's been about 2 weeks since I looked at things under the hood. I have the surging idle problem only in drive or reverse. I also thought about it some more, and it usually happens more when I hit my brakes. I am thinking it is the vaccum line that goes from the brake master cylinder to the back of the engine. If any vaccum line was cracked, it would cause a weird idle while in drive if I was pressing the brake?

I watched the guages and noticed when my engines idle decides to dip and surge, so does my battery and so does my oil pressure guage. I don't know if that helps, but that is what I am watching.

While driving the oil guage stays above the half way point at all times until I come to a stop, then it goes down to what looks like the 10psi mark or so. The 10psi mark is just an guesstimate of what psi it is at. Car has new tranny fluid, new oil, new plugs, new wires, PVC is semi-new, fuel filter is original (almost 64000 miles), O2 sensors look stock, changed IAC and EGR and ECT, oil pressure sender is less than a year old, TPS sensor is stock I beleive. IAT looks to also be stock.

My car throws no codes which makes me think it is a vaccum leak. It is really just starting to annoy me. My car idles fine when in park or netural, but once it's placed into drive, that is when the rpm's seem to surge.

Any help or idea's would be great. I have a new fuel filter in my house which I thought about putting on at the same time I do my LCA and Panhard rod bar install. Any ideas would be wonderfull.

Thanks again guys,
Chris

[strange_trp]

could be leaking from brake booster vac hose, one-way check valve sticking into vac booster, or the vac booster itself. use a propane torch to locate the leak.

[99Camaro99]

had similar problem and factory said they replaced my O2 sensor and the MAF screen...so go figure...either way problem is gone

[spunger]

I was told that the O2 sensors would not cause this problem even though I have thought about replacing them anways since its been probably 64000 miles on them. If someone gives me a good reason to change them out I'll do it.

I am going to double and tripple check the vaccume lines this weekend, and also change out the fuel filter if I have time since my gas is gettin down there.

Please, any other ideas let me know,
Chris