Hoichi

My 1992 LS 400 has a TSB EG-001-98 for the problem relating to engine sputtering when outside temperature is hot. When I restarted the engine, the RPM is getting erractic. I have replaced the crank, coolant, coil sensors with no avail. Do I have to replace the EVAP, charcoal canister or fuel filter which has not been replaced for a long time. When the car is cooled down for a couple of hours, it runs perfect again. Please help.