A series of problems, '93 Grand Marq.

[hemi_fan]

I've been having a bunch of problems with my rather tired out Grand Marquis, the first one is really annoying and I fear it'll get worse, the second is dangerous, and the third is less important, anyway, here they are;

1. When I get in the car and go to take it out of park, I have to depress the brake EXTREMELY far now to get it to come out, its actually to the point where sometimes I worry I might break the seat mounts because I'm standing on the pedal so hard. After the brake is far enough it slides out of park like nothing happened. I'm worried it'll get worse and just be stuck in park.

2. When driving in extremely heavy rain with the wipers on full-blast they seem to not go any faster than the 2nd fastest setting. Not only this, but they will gradually slow down and have even come to a complete stop for several hair-raising seconds as I try to drive down the highway blind. After a short break, they kick back in but still going slower than they should.

3. On start-up the car often chugs and bucks a fair amount, and once stalled out on me. The computer then kicks in and raises the idle and it seems to run alright, however a recent trip to the drag strip showed me that I'm down on power when the best run I could muster was an 18.3 at 76mph, and the last run of the night something happened where in 2nd it blew a bunch of smoke out the tail and ran a 22 second pass at 71mph. I do get a CEL pretty much every time I drive the car, usually after its warm or when I get on the highway but I haven't checked codes.

[drock96marquis]

1.)
There actually isn't a mechanical connection between the shifter locking and the brake pedal, it's electronic. The pedal could be depressed a 1/4" or to the floor, makes no difference.

Most likely your brake lamp switch (aka BOO or stop lamp switch) and/or it's wiring are faulty.



Take care not to pull on the shifter too hard or you risk snapping the gear shift tube, which is a little more difficult to replace than a brake lamp switch


2.)
Does messing around with the wiper switch (MFS) have any effect?

If not, I'd suspect the WCM (wiper control module). It is what actually controls the wiper motor intermittent and high speed functions.

I would also FIRST REPLACE the circuit breaker for the wipers, which is in the #2 position of the interior fuse block





3.) Could be the IAC (idle air control) valve sticking

But if your EGR is sticking that could also cause similar concerns.

Change the fuel filter and clean your mass air sensor.



Find out your check engine codes then get back to us. You will probably have one for EGR, which is a common issue for 1991-1995 4.6s as the EGR channels like the clog (partly because the valve stem seals of this same year range leak and let your engine burn oil)

http://www.troublecodes.net/Ford/

As for your drag times, unfortunately that's not far off from where you should be.
1992-1994 models are especially slow. From the factory they were low 17s, your car is probably up there in mileage now I'm sure and we don't know it's true mechanical condition.
If you had an EGR problem allowing flow when it shouldn't, this would also cause power decrease and the idle stumble.