On my 80 after I ran it with ethanol free gas for a few months got extremely smooth. An 80 typically gets rough idle with dirty or faulty injectors as well as wiring issues forming near the egr. In general in line 6 cylinder engines should be pretty silky smooth. Now to be fair I have advanced the timing a little on mine also.
My 80 is my newest vehicle but I do drive a 100 series and an early Sequoia from time to time and those are very smooth.
The only Lexus car i have driven was also next to impossible to feel anything an that was a 19 year old car.
I can speak for the new car but i can say the 80 can run smoother and it will once you find the issue.
My last 80 was used and abused and it was glass smooth. On this current 80, it has a much more extensive service history and in 5X better shape, so it is puzzling.
So far I have replaced almost 8 feet of vacuum hose (some of it preemptive, some of it was cracking and dry), replaced the charcoal canister and gotten EVAP working again, verified EGR function, cleaned the modulator filter, did the brake booster hose and check valve, and replaced the cap and rotor. It feels night and day.
Next she's getting new O2s - the rear is throwing an intermittent P0136, hopefully a new LandTank MAF, and doing the Hudd EGR delete.
She already has the old sewing machine sound back with just the work already done, and it seems the EFI is getting closer with every drive cycle. I have no doubt that one day very soon she will be perfectly sorted.
I don't mind running higher octane fuel, since it isn't a daily driver, so definitely going to advance my timing a few degrees as well, and double-check the idle speed...I have noticed it hovering on the southside of 650 a little too much for my liking.
Cheers!
