1992 Grand AM SE Help

Purchased this car about 3 months ago, and even for the few little problems it's had so far i'm loving it. I've done a few searches to try to fix the problems, but usually come up empty handed so I was hoping someone here could give me a hand

1992 Pontiac Grand AM SE
4 Cylinder, Quad OHC
138,000 Miles
2 door

Problem #1
Bought the car with a water leak in the rear drivers side. Shop vac'd the heck out of it, left the windows open in the hot weather and finally had the car dried out. I removed the wiper blades and the black trim underneath and cleaned out in there, near the intake for the A/C and the blower motor. Since I did all that I haven't had a water leak. Today, one of the worse rainstorms we get in New York, the problem came back with a vengance, with about an inch and a half of water on the passenger floor. I don't think it's a trim leak or anything like that simply because the water pools there, only there, and no where else is wet. The carpet everywhere else in the car is dry. It's almost like the water rises up from the flor itself lol.

Problem #2
Not a big problem, something I can live with but if anyone has dealt with this i'd like to know how to fix it if I would ever come about some extra cash. Fuel guage, when the tank is full often reads far further to the right then it should, again not breaking my heart to have it fixed

Problem #3
The car has suddenly developed a problem with the speedometer. From stop with the throttle pressed approx. 25% or when floored on the highway, the speedometer will often fluctuate, dropping anywhere from 5 to 25 MPH, and all the way down to zero. This problem usually fixes itself once the car shifts to what feels to be 3rd gear or under when the throttle is let off a little. This problem bothers me simply because it affects the cruise control lol.

Any help at all would be appreciated

I wish I could help you with the water leak. I have the same exact problem with my 94 grandam se. I have been told this is a common problem with grand ams. People have posted about this before so try to run a search. So far nothing has worked to solve my problem, but my hubby drilled a small hole in the drivers side floor to allow the water to drain. In freezing wet weather, I would have a sheet of ice on the floor! What's really strange is a few months ago I noticed the problem seemed to go away on it's own (we did nothing that we knew of). But a few days ago I noticed a small wet patch again on the passenger side.

Most searches i've come up with address this issue on the passenger side and in the front unfortunately. I'm going to go to Pontiac on Wednesday and see what they say, either that or see if my old boss will let me use the computer at the Chevy dealer I used to work at and see exactly what that TSB says lol

I had a water "fountain" at passager side, it was leaking below the front panel somewhere. Traced it down for weeks, months until I found it. The water leaking was coming down by the fan ventilation passages. It took me to disassemble all the black plastic grille outside, between the front windshield and the engine hood. It was necessary to access the ventilation fan and its plastic box. The external grille allowed external air to get to the fan, but it has someking of trap in the middle to avoid rain water to get to the fan, it is like a box that deviates the water. There is a kind of a controlled small door, electric actuated that open or closes the air way. This door sits vertically at the side of the water trap box. The box is made in plastic and where the door sits is very fragile (thanks to Pontiac). The box wall near to the door was broken down to the base of the box, so instead to funel the rain water to the asfalt the broken (and missing) plastic was delivering water directly to the air path to the car interior... nice. I just glued a piece of 5mm tick pvc plate cut to seal the missing part and also glued another piece of pvc to cover the box. If Pontiac design engineer used the brains, it would made the box closed on 80% to the right side (where the door sits) allowing only air (and rain) to come by the left, where there is a nice deeper base (where the water drain exists), water would never hit the right side. The fix took 2 to 3 hours, since it required to remove the grille completely, windshield blades, and a bunch of screws. At the end I thought it could be easier if the engine hood were removed, but then, who knows the problems to resit it.