I'd try to figure it out. Bubbles in the system ain't good. If the temp sensor is bad it will be dumping fuel. Same with thermostat eventually sticking open. It will not stay at optimal temp. Stuck closed and over heating problems.

Last check for any coolant leaking any where. Front of engine. Water pump area. Radiator cap... etc..

 

I agree with @MikeFig82 , it's best not to leave coolant related issues unaddressed. I had a 76 Mercedes 280S that needed the radiator rodded out, it ran fine except on days when it got into the upper 80's and 90's (very common in Southern Cal). I waited to long and I ended up with a cracked head and head gasket leak. Ended up costing me a ton of money, the job was never finished and I ended up just parting it out...

 

So you guys think it’s either air in the coolant lines, thermostat stuck open or a bad temperature sensor? I’ve checked around ALOT for coolant leaks, can’t find any.

My car was at the mechanic today. They said bleeding the coolant lines was a waste of time because if there was air in the lines it would also cause the gauge to go above the middle. They said my thermostat was fine, but the temp sensor hasn’t been addressed. Their reasoning for the gauge dropping under hard acceleration was that my temperature sensor must be ‘very sensitive’

I’m not comfortable doing this type of work on my own. So should I just bite the bullet and take it to a Lexus dealership? These mechanics don’t seem to be very helpful. I just want to make sure there’s definitely something wrong before I start shelling out money for this. Appreciate all the help!

 

At the very least get take it to the Lexus dealership to try and diagnose the issue. My local dealership charges $120 to do diagnostics. At least you can figure out if you have a problem or not

 

Will do. Thanks

 

If you are handy change the thermostat It’s only 3 10mm bolts. Just make sure to hit them wd40 or some other penetrating oil a day before you intend to remove them and don’t aggressively remove them as the housing is aluminum and you don’t want to strip them or break them off. Also be sure to buy an OEM thermostat not a jobber OEM in Canada runs around $54 jobbers are half the price. It’s going to need to be replaced In year or two anyhow so no harm in doing it now

 

Well the Lexus dealership diagnosed the issue and said nothing is wrong, so I guess I’ll just leave it be.