So here's ths scoop. I bought a 2010 is350 in February with ~114k on it. It had the fsport intake, and exhaust. I mash on it fairly often, but i try not to push it too far. I change the oil every 3-5k, tranny fluid at ~120k, and did the plugs at 127k.

In the few months I have owned the vehicle, I have noticed the car has gotten much louder and tends to pop on deceleration or when I let off.

If I'm driving normally, the rpms will randomly dip with consistent throttle. Misfiring maybe??

lastly, the transmission tends to jerk a little. Mostly when coming to a stop, but happens a lot during normal shifting.

i scheduled an appointment with kuni lexus to possibly diagnose these problems, but has anyone else experienced anything like this?

 

Check for vacuum leaks and/or exhaust leaks. Both could cause popping. Exhaust leak is far less likely to cause shift issues.

Did you use Techstream for fluid change? Just measuring and replacing fluids at different temperatures (same apparent volume) could yield different fill volumes.

 

how would I go about checking for a vaccume leak?

I'm not sure honestly. I got it done at a local Oil Can Henry's. They had me "cycle" my fluid at least 9 times before it was completely fresh...