As for the misfire, my LS had a misfire occasionally, and it turned out to be dirty multiwire connectors at the ignition modules down near/under the cruise control actuator can to the right of the air filter box.
I cleaned them thoroughly with spray electronics cleaner and then applied some dielectric grease to protect them from the dirt and water they can be subject to in that location. Cured the problem.
Which plugs are you using? I found that the NGK Iridiums are the best for the LS. No fouling at all.
Should be able to find a good used seat for the LS, at the rate these cars are parted out due to people not willing to repair the damage due to a skipped timing belt. Probably cost less than having a seat recovered, including shipping.
Be aware that 164s have a problem with the short immersed fuel hose attached to the fuel pump inside the tank. That hose craps out maybe around 100k+ miles or so. Had it happen to my 91S at about 110k miles, and am going to change in my LS, it now at 110k miles.
1989 Milano, Shankle Sport
1991 164S, stock
1994 164LS (~Q)
1972 Morgan 27
previously owned since 1964:
62 Morris MiniMinor 850, 67 Austin 1275 Cooper S (Downton 3/4 race), 64 Giulia Sprint GT (1st red one made), 72 Fiat 128 Sedan, 75 Alfetta Sedan, 78 Alfetta Sedan, 78 GTV, 81 GTV6, 86 GTV6
Last edited by Del; 07-17-2018 at 10:59 PM.