Hello Mr.Scotty
I have 1998 Lexus LS400 with 168k mile
1st problem ... While I'm driving, suddenly RPM drop and there is no acceleration, I should press hardly on acceleration paddle to accelerate again.
2nd problem.... when I stop at signal light i feel there is hesitation ... if I shift the gear to (N) or (P) still there is hesitation.!!!

No check engine warnings at the dashboard
Throttle body cleaned recently
Before 2weeks I have changed spark plugs, air filter intake & fuel filter ...... all are geniun parts
Still there is hesitation & it's doing 10MPG😓
Help me??!!

those are notorious for bad main computers, a rarity for toyota products, but one that exists. Check that first, it's the only thing I ever saw make those get 10 mpg