Does anyone know where I can have my engine rebuilt? I rather rebuild the one I have than to buy 1 and have it rebuilt.

 

Jesus Christ man.

1.) Rebuilding is far more expensive, time consuming and labor intensive. So, that either means you'll be paying a lot more for labor, or spending a lot more time DIY'ing.
2.) Finding a low mileage junkyard engine is far more sensible/efficient/economic. It's far easier to remove one, and then drop one in than it is to remove one, crack it open, install rebuild parts, then drop it back in.
3.) Have you checked your regional forums/shops, etc?
4.) Why do you need a new engine, a little background would help.

 

My engine has 280K kms on it (Maxima 96). When I drive above 130km/hour it burns oil and pushes it out. It smells inside of the car and causes headache during long trips. The engine is very smooth but very slow to accelerate. It was pretty shameful for Maxima to give up to Camry. Sigh. But it still makes 650kms per tank on highway and 400 km in a city – what is not very bad.
The car itself is in a great shape and it is still looking good. I took a look at a couple of junk yard engines and they are not very impressive and it looks like they have the same issue. My idea to buy engine rebuild kit and replace pistons, rings, timing chains – it may help. I approximate to spend around $2000 – it is much cheaper than to buy a newer car and result is more predictable – I will be sure in my car. I did this before on my previous car including crankshaft and cylinder polishing but it was in Europe. Can someone advise how it can be done in North America? I would be happy to install some tuning goodies as well.

 

If slowness isn't related to maf/ks, etc, have you replaced or gutted the cats? With that kind of mileage they must be clogged to hell.

That's not a lot of mileage (I mean Kms ) for a 3.0 to be crapping out unless it wasn't maintenanced well.

 

When I bought my car it had 1 liter of oil in it only. Thus, I assume it is a maintenance issue - aka lady driven.

Thank you for the idea to check cats.

By the way, how to check this without taking it apart? I am a little afraid to take off rusty nuts without having a replacement.

 

Most muffler shops will test your cats for free. They take a temperature reading on the cat while the engine is running. I had a 1998 Honda Accord with a failed cat and they figured it out in less than 10 minutes. But the Accord was throwing codes for the cat so I already knew something was wrong.