95 300zx sounds like a muscle car help :(

[Kuragari]

ok i have been browsing the forums forever and have found a few solutions but i thought i would go ahead and actually post something.
My Z sounds like a muscle / drag car... its awe full.. I was told it has a vacuum leak but i dunno yet.
It has no low end power, sometimes the idle goes up and down very fast between 800 - 1200. Its very loud and throaty. When coming to a stop and down shifting there is alot of back pressure and popping coming out of the exhaust. Sometimes if I dont downshift and just put it in neutral and coast the car will die. Ive done the coilpack test and everything is working fine on all cylinders. It just feels like im trying to pull an 18 wheeler or something. I can barely keep up with traffic and the car screams like im hauling when im going 20 mph... I mean.. it feels like it wants to take off.. but it doesnt. And 1st gear i have to rev it up to even move so it wont die. I have another IACV to put on it.. that should take care of the idle.. but what about the power and sound? Any suggestions? :022:

[mrmoose]

Def sounds like a vac leak. But also do a basic tune up, plugs, fuel filter etc. Is your car stock?

[Kuragari]

yes everything is stock. Im gonna test the injectors today and try and do a vacuum test.

[nissanfreak12]

How long ago was the timing done?

[Kuragari]

honestly im not 100% sure.. the guy i bought it from replaced the engine and a whole bunch of stuff. He said all that was good (not that i should take his word for it) but he said it has a vacuum leak.. I am just not able to pin point it. im also trying to rule things out. Im guessing i should go ahead check the timing... I also had to adjust the TPS which improved it a little.. still very sluggish though.

[nissanfreak12]

It almost sounds like you jumped timing, but just speculation. Another thing to also check out is the O2 sensors, this will also cause your car to have idle move up and down like that.

Have you done an ecu diagnostic? I would definitely do it in mode I and II, mode II is for the O2 sensors. Look in the manual for for what to look for and how to do it.