Bostech

Originally I was thinking about selling car as I bought Lexus but I am not impressed by Lexus as I already spent 1000 on repairs so might as well keep repairing 02 and 06.
So I am hoping engine did not overheat and got mechanic who could overhaul car...I am thinking about doing timing belt/water pump (old mechanic lied about replacing it) with serpentine belt...he would also do rear main seal which leaks then as far as I know should replace oil pump seal,crankshaft and camshaft seals...power steering leaks too so not sure what needs to be done there. I had rack and pinion replaced with reman unit in 2017 and in 2019 axle shafts.
What else should I try to replace while he is doing timing belt kit and rear main seal?
It also leaks "at transmission" so not sure where and what needs to be replaced...is that rear main seal or something else?
For 8 years car would occasionally surge when shifting I think between 2nd and 3rd..I would just let go of gas and step on it again and car would continue as normal.Sometimes goes weeks without doing and sometimes does it every 2 days.

My goal is to have car that is drivable and does not leak oil/fluid,it will be mostly driven between store/home daily and as backup if my other RL is in shop in which case it might need to do 40 miles a day for while so basically make it dependable but most of time not heavily used.
By the way 2002 RL stereo is waaay better than 2011 Lexus,even that I need new brakes and rotors still brakes better than Lexus which has spongy brakes and once you load car with AC on it still pulls better than Lexus despite having 40 less horsepowers.

1186KA9

I'd just change all the fluids and check out the suspension for damage and the frame/body for rust while that's all being done. Do a 3x drain and fill on the trans and change the diff oil along with all other fluids. For the trans, I recommend Redline D4. My 04' shifts great with it. Granted I am using Lubegard Black in conjunction with it, but it shifts way better. Only use the Lubegard black if the shifts are too rough for your liking. The trans should be fine with just straight D4. I'll give suggestions on which parts to use to get the OEM feel if you need it.

PS: Mobil1 0w40 FS works wonders with this engine. Engine has never run this quiet in my life! Just make sure to get the API SP version cause that's what I'm using. Should be able to find it at Walmart for about 30 bucks or so. I use a Purolator Boss oil filter as well.

Bostech

I did 3x3 transmission fluid change back in 2018 but it still surges once in while and has been doing it since 2017 or so.I use Honda oil and Mobil 5w30 synthetic.There is no rust since I am in Florida and suspension feels fine,rides straight.

1186KA9

Well, depending on mileage, I'd still do the 3x drain and fill. Do the filter as well on the last drain. Its right behind the trans pan when you remove it. Only takes 2 or 3 10mms after the pan to drop it. Z-1/DW-1 is not durable at all. It shears pretty quickly compared to other atfs. Either use DW-1 or D4 if you do the 3x. I'd potentially look into the mount as well. Its usual for the trans mount to go on the Legend IIs and IIIs. It might be hard to source Mobil 1 0w40 FS in Florida. If you can though, it does make a difference. I'd still go around the suspension and either grab the arms or use a prybar to see if there is play. Also, if you can, adjust the cold idle air valve. That will change the idle/engine response though, so expect to do a idle relearn. I'll post the SM docs as needed.