i have an sc300 with a jdm 2jz-gte non vvti and here is my list of problems ..please help...

this all started happening after my water pump blew and coolent got all over the alternator.......water pump is now fixed but here are the issues

1.idle jumps from 600 to 1000rpm and my headlights get dim everytime the idle goes down and get brighter when idle increases..

2.when driving, everytime the car reaches 2500rpm the car sputters and when it gets past 2500rpm it goes back to normal.....

 

i just did and aristo swap in my SC, once it got running the same thing happened. sounds like you there is a problem with the wires that communicate with the alternator and ecu.

 

i would think the same thing. maybe take your alt off and have it tested. then check all wires and connectors.