My car dose this weird thing when you drive the car when the engine is cool, say the first drive of the day of if the car has been sitting 3+ hours.

When you turn the car on then start to drive it will hit 2500-3000 RPM kinda hesitate and make this sound that I can really only describe as someone taking a wrench and hitting it on something metal or maybe a small firecracker under a metal bucket.

It only dose this once or twice then it runs fine. If the engine is warm or I let it warm up for maybe 10min it wont do it.

I haven't the slightest idea what it could be and I can't really show a mechanic because it wont do it unless I leave it with them overnight.

Not sure man...I'd start with ignition timing. Use a timing light to check it. I just bought one and fixed my Z with it lol. If you ever want some help or need to borrow a tool or anything, holler at me man I'm right down the street from you!

My timing should be right at 15* I just had it set maybe a month or so ago at 3SX.

is it a backfire? haha

That's what it may be. I don't know what could be causing it though. O2 sensor maybe?

maybe a bad o2. Probably a failing injector. ohm test the injectors or do the screw drver test ( put a long screw driver up to the top of the injector (assuming u know where they are) then put ure ear to the driver ull hear it going tick tick tick listen to all 6 injectors if ne of them sounds very different then the others or more than one sound very different its probably a problem with that injector. U can temporarily fix it by smacking the screw driver with a hammer lightly will free up a stuck injector.

I'll have to check the injectors, I have 4 new ones and 2 old ones lol

preignition

could be a lifter sticking

I do occasionally have that lifter tick.

Anyone know roughly what a total engine rebuild would cost?