[bond1]

The V6 engine in my 98 taco rattles, intermittently, hot or cold. The engine only has 50,000 miles on it, so this shouldn't be happening. It only rattles when the RPM's hit around 2000, while i'm driving. If I floor the gas the rattle gets louder, but it diminishes when the RPM's hit around 3000. Sounds like its coming from the back of the engine near the firewall. I tried changing the oil thinking low oil pressure. No change. I added marvel mystry oil to the engine oil, no change. I changed the high performance plugs out with standard plugs thinking detonation or pre-ignition. Rattle's still there. I took all the belts off the front thinking bad pully bearing. No dice. I added a can of fuel system cleaner to the gas, no change. I fueled up on high octane gas, and it sort of toned the rattle down, but not much. I checked the heat shields on the manifolds, they're tight, no cracks. The rattle sounds metallic, like valve clatter, its definately engine related. The previous owner had the truck supercharged, but put the stock manifold back on the engine when he sold it to me. I can't think of anything else to check. I'm going to try to disconnect the cat converter to see if that's where the noise is coming from. I can also make the rattle occur when i'm parked, but the rattle happens at about 3000 rpm. Any body else have this problem?