SimonJ

So, I just recently bought this ls400 (240k miles) and the car seems to run smoothly under normal driving.. Until I try to put my foot down, the acceleration is very slow and hesitant, slower than 1/2 throttle it seems. The full throttle upshift is very jerky as Well, as if I'm towing something.there is a CEL (don't know what it is yet as I don't have an OBD1 scanner). I'm hoping it's something simple like spark plugs or coils(which might be the originals for all I know) or an ecu or tps problem, either way I'd appreciate some advice since not many others seem to have this Exact problem.

python

iTrader: (4)

scanner wont tell u anything..do a complete tune up

213374U

Yup, give it a general tune-up and then go from there. No sense trying to hunt this down if you don't know the state of your ignition components.

python

iTrader: (4)

if that doesnt work..maybe ecm re-cap time

SimonJ

Update, I've replaced a few parts: spark plugs, belt(it broke off) air filter and thermostat; which was partially responsible since the engine was never getting up to temp. I've also gotten an oil and coolant change, because why not. End result is better performance around 50% of the time. However the engine sometimes still loses power at 3000rpm and makes a faint squeaking noise. I believe I've narrowed down the options down to the TPS, ecu capacitors or o2 sensors. I feel like I'm getting closer to solving the problem, it's just the inconsistency of the engine's performance that is stumping me at the moment

213374U

Did you replace plug wires, distributor caps, and rotors? If not you haven't addressed your entire ignition system.