Vibration and loss of power at or above 3,000RPM

[cjserio]

First of all, i don't have an infinity...I have a 1994 Nissan 4x4 Pickup (5 speed MT) with a KA24E engine. I have 170k miles on the vehicle and i bought it just a few thousand miles ago.

When i accelerate, the engine seems to perform fine until I hit 3,000 RPM. The engine then gets very loud and seems to vibrate...It's not a rattle or a shake...it's like a very loud hum. It's very difficult to get the engine to continue accelerating about that point. I can eventually get it up to 5,000RPM but the engine feels and sounds like it's in pain.

Here's what i've done so far...

- Cleaned the Mass-Airflow sensor- Installed a new Throttle Position Sensor (mine died)- Brand new plugs- Brand new Catalytic converter- Checked the Dist Cap and rotor- Checked the air filter- Tried 3 bottles of fuel injector cleaner- Tried a SeaFoam treatment in the gas, the brake booster and oil.- I don't see any cracked vacuum hoses- The plug wires are fairly new and i don't see any arcing.

Someone please help me get this engine running right! Thanks!

[Vegascorbin]

any codes?

[cjserio]

Nope no codes currently. I forgot to mention that my mechanic supposedly adjusted the timing. He said it was off a degree or two but it don't notice any difference at all.

[USMCgetsome]

timing is way off!

[cjserio]

Um...I said the timing was only off a degree or two and was corrected with no noticeable difference...

[tero404]

this is going to sound really silly but... check ur crank pulley and make sure its on tight.