Full Throttle Behavior
 

I was cruising along around 15mph in my '94 LS400 when I decided to "see what she could do" and floored it. The engine revved up and, to my horror, right when I expected the transmission to shift, the engine hit close to redline and it sounded like a rev-limiter kicked in and I felt a loss in power until I let off the accelerator. All maintenance is up to date on engine and trans, with the exception of an EGR CEL I will be fixing shortly. Any ideas here? This cannot be normal behavior, can it?

Almost sounds like the transmission momentarily slipped. Have you checked the fluid level lately? It shouldn't be able to hit the red line in 1st gear at only 15 mph.

So there was no gear shifting at all. It sounds like the ECU is partially dead or malfunctioning. Remember that the gear shifting is done by the ECU.

A delayed gear shifting or a no gear shift is one of the early symptoms of the failing ECU or the input signal to the ECU is not sufficient. Check the DIAG code and the ripple. You can find those ways at the FAQ page.

Dunno for 1LS, but on my 2LS if I put the transmission in first gear and floor it, it will stay there and hit the limiter until I tell it to go in second.