My car starts to shake after about 35-45 mph

check motor -tranny-transfer case mounts ===check shifter and bushings

tires out of balance?

Do u mean ur sway bar and if so check for loose bolts or bad bushings good luck hope this helps

It could be a fuse problem or it could be a defective fan motor.

After you had new tie rods and rack and pinion did you get a complete alignment on the car? Also you may want to check all 4 tires to see if they are balanced correctly.

RACK PINION THE RACK PINION IS THE ONE THAT TURNS THE WHEELS LEFT OR RITE

Well, assuming they actually checked all the bushings, ball joints and tie rod ends that only leaves the bearings/races and rack-n-pinion to check. You also need to check your motor and transmission mounts and bushings as well as the u-joints on the drive shaft if this is rear wheel drive.

check if you got rack in pinion steering the mounting bolts for looseness .check tie rod end housing seats and the inner tie rod ball studs for wear.if all is good.your rack has worn pinion bushing and rack bushing.

What is the actual problem?

If the vehicle shakes all the time when driving, it is possible a coil pack fault, and yes it is common, if it shakes when you get toa certain MPH, its possible tyre fault or wheel balancing

Check your pinion angle. I bought my car from a guy who changed the tranny upwards of 6 times. i figured that the stock tranny couldn't handle the power but as i checked into it, my pinion angle was wrong. I changed my bushings and put new rear control arms on. Knock on wood its worked longer than any other tranng. Check to see if your leaking out of your tail-shaft on your tranny and if you are i believe that the rear bushing on your tranny is bad as well and that may cause vibration. Also i heard from a guy that the urethane bushings in the back (which I have as well) may cause a problem with your welds that hold the spot where the control arms mount up at. Check into a torque box. I've had no problems but I'm just warning you.