I recently purchased a 96 es 300 with 166,000 miles. The check engine light came on so I had it checked today. The code came up as P0121. The recent owner did purchase a new battery so the idle was kind of high but after looking online I believe I reset it correctly. The car goes into gear fine and the accelerator doesn't stick so I'm just asking for insight if the Throttle position sensor could be faulty and the main cause of the check engine light coming on?

 

That's a fairly specific code either the TPS is bad, wiring/connector going to the TPS or a bad ECU (not likely). Search Ebay, Amazon etc. for 89452-32060 or hit a salvage yard.