I have a 91 ls400, was sitting for a year got the tranny replaced and know when I try to do a 0-60 it starts to buck until i let off the gas. I put some fuel injector cleaner and the car stops bucking as bad. Do I need a tune up or a new fuel filter or fuel pump.

 

How much has it been driven since it was parked for a year? Could be bad gas, or a sticky fuel injector. If so, easiest fix is more cleaner & run a few tanks of fresh gas thru it. If it's sat with less than a full tank there's a possibility of rust/contamination which you should see by pulling the fuel filter, which would be a good time to replace it anyways. I think the fuel filter on your car is just forward of the rear axle on the driver's side so it's easy to get to, if you don't want to replace the filter I'd at least disconnect the fuel line from the tank to the filter and catch some gas in a clear jar and inspect it.

 

Thanks will do, I appreciate it. You don't think that it could be spark plugs?

 

check spark plugs/wires/rotors/caps/ignitors, and make sure trans has Toyota T-IV fluid, not dexron.