crank no start no codes, why?

I've replaced tcm, ecm, fuel pump, sending
unit, coil packs, injectors, crank shaft
position sensor, camshaft position sensor,
iat, iac, map, tps, coolant temp sensor,
power steering pressure switch sensor, and
ignition switch. ive cleaned the throtle body,
and re did all ground connections under the
hood. replaced the air filter. checked all
sensor conectors for correct readings with
multi meter.checked all fuses. tested all
relays. it used to start if I stepped on the gas
now wont start at all, no matter what. it
started messing up on the way home losing
power having to floor it to keep the rpms up.
I couldn't go faster than 45mph. I made it
home and haven't been able to fix it. what
else could cause this?