I have a 99 SF and i had the same thing, it was bad front break pads. the 99 has two caliper pistons, figured one as pushing harder than the other and that caused the break pads to wear into a wedge, i changed the pads and the vibration was gone. a few days later i noticed it again but this time with a break burning smell. the drivers side caliper is sticking, just finished changing the drivers side caliper, taking a lunch break now, will change passenger next. Iam using the old(new) pads and not cutting or changing rotors this time around. next break job will get rotors and pads. going to bleed the breaks the old fashion way as I ordered a Motive Products Custom Ford Power Bleeder(0107) Ford 3 Tab bleeder last Sunday but its not going to make it here till Tuesday :-(. I will flush all four breaks next weekendnope, the vibration happens at exactly 2600RPM in every gear. It causes an interesting harmonic in my seat base.
It was doing it before the snow...
Hardest part was getting the vehicle clean and dry and the garage up to 65 degrees it is 32 here today. The install took less than thirty minutes and that is with being extremely picky with the template placement. These install with two sided 3m tape so any water that gets in would be on the rear facing ends that have no tape on them from the factory. I would assume that this is to let any water that does get in out. I would think you would be causing more problems by trying to seal them up than you would fix. I have never seen rust behind this type of moulding and I have been around body shops my whole life.How hard were they to install and did you do anything special to keep water from being able to get behind them?
How many miles were on the plugs?Engine out, heads off! Damn head gaskets! Rest of the engine looks good though. Spark plugs were WASTED!