Updated to include part # for Idle Air Control (IAC) Valve Gasket
Gaskets Ordered for Starter Replacement
Throttle Body Gasket 22271-50010
Intake Manifold Gasket 17171-50010, Qty 2
Air Surge Tank To Intake Manifold Gasket 17176-50020, Qty 4
Idle Air Control (IAC) Valve Gasket 22278-50010
EGR Pipe Gasket 25634-50010
EGR Valve Gasket 25627-50010
Water Outlet Gasket for Rear Coolant Bridge 16341-50010, qty 2
Fuel Injector Insulator 23291-41010, qty 8
If you're doing the Starter you may want to perform:
Parts Ordered For Valve Cover Gasket Replacement
Gasket, cylinder head cover 11213-50021 (qty 2)
Gasket, spark plug tube 11193-15010 (qty 8)
Washer, seal 90210-07001 (qty 16)
Throttle body gasket 22271-50010 (qty 1)
PCV Valve 12204-50011 (qty 1)
Grommet, PCV Valve 90480-18001 (qty 1)
O-ring for oil dipstick 96711-19010 (qty 1)
FIPG, form in place gasket 00295-00103 (qty 1)
Parts Ordered For Starter, Distributor Cap & Rotor Replacement
Starter Denso 28100-50020-84
Distributor Cap 19101-50020 (qty 2)
Distributor Rotor 19102-50020 (qty 2)
Spark Plug Wires NGK
Spark Plugs: NGK G-Power BKR6EGP 7092 Platinum Alloy
Other Procedures
Check Throttle Body & Linkage, Cruise Control Cable
Clean injectors, clean intake parts, clean throttle body.
Replace Battery Terminals Clamp (+)
Check Coolant Bleeder valve washer & clamp
Regarding the starter, you may not need to remove the rear coolant bridge if you have the correct flexhead 14mm wrench to remove the starter bolts. You may need to soak them with PB Blaster for an easy removal. https://www.clublexus.com/forums/ls-1st-and-2nd-gen-1990-2000/194735-ls400-starter-replacement-a-story-by-bdr.html