Yeah, I've also heard that the V8 engine is very unreliable for a Toyota engine.
I think it is mostly due to lightweight aluminum casting used throughout the block and heads.
Also, the timing belt, which is prone to breakage, should be replaced by a chain.
THe silica-filled intake valves have been known to fail under high-rpm operation.
If I were you, I'd trade in that V8 before it's too late and replace it with a V6 version.
BTW, I'm just kidding
I'm sure the V8 is just as reliable as any other Toyota engine these days. If you drive a Toyota, reliability should be the last thing you worry about.