I have a 1999 dodge ram 4x4. I replaced my brake MC and I bleed the brakes but I am occasionally still getting a soft brake pedal. Any ideas. No leaks and not loosing any fluids.

sounds like hydralic leak where your brake pads and shoes are located.

bench bleed the master cylinder then start bleeding at the rear passenger then rear driver, front passenger then finally front driver hopefully that helps you

Loosen the bleed ******* off 1 at a time , if no fluid comes out the nipple is blocked clean them or change them .

Did you bench bleed the MC before installing it? If not, that's the problem. MUST be bench bled or you'll always have air. If brakes lights are on, the brake switch is out of adjustment OR (since you replaced the MC), the push rod is out of adjustment

Not likely that the booster is an issue. The booster would not be able to overcome the brake fluid compression.
First open and inspect all brakes for leaks, adjustment, etc. Check all brake lines.
So if no leaks, did the fluid go low in the MC? If so, pad consumption would eat more than a MC reservoir of fluid, and not require MC replacement, but rebleeding and top up of fluid. If the pads are worn, and you replace them, often this will expel air back through the MC.

If you determine the MC is faulty, bench bleed the new one before install, or you will have lots of problems getting air out....

try bleeding the master cylinder at the lines first as it indicates that there is still air in the pistons
loosen one line at a time and gently apply the brakes until any air bubbles come out tighten the line before releasing the brake pedal
do it for the other line and then bleed all the brakes starting at the longest line first and ending at the shortest line

It sounds like you have a bad mastercylinder cause when you panic brake it doesn't have time to bleed through the valve in the cylinder but under normal braking your foot is on pedal longer in turn giving the fluid time to bypass the valve in the mastercylinder in turn the pedal going to the floor.

Try doing the following: Bleed the system, starting with the wheel the greatest distance from the master cylinder, working your way to the wheel closest. Bleed the system to completely replace the fluid. This is a good idea, as sitting for 3 years is bad for the brake and fuel systems. The brake fluid may be contaminated (small amount of condensation in the system can cause failure of calipers and brake cylinders) If the pedal is still hanging up, and not returning all the way, you probably will have to replace the master cylinder.

did you bleed the brakes in the proper order? RR LR RF LF. check rubber lines for deterioration or BULGING when you apply brakes.

Try having the dealer flush and bleed your system. It is very hard to bleed ABS systems yourself and have safe brakes that still work afterward. Bleeding non-ABS brakes yourself is easy not the same for ABS brakes. Valving, sensors and what-not require a tech and the correct equipment in my opinion. You do it wrong and you could ruin your ABS system. Do that and see if they firm up. I replaced my brake shoes/pads at the same time all new everything in back, drums/springs everything and new rotors up front. then I had the chevy dealer flush, refill and bleed system. Stiffer pedal and brakes work better. Keep in mind the brakes on 99 Tahoes are inaedequate, require new rotors often, heat up and fade/glaze pads regularly. I replace my pads long before they wear down because they glaze up and start fading early. I'll rough em up once maybe, next time, new ones. Every two brake jobs, new rotors for me. Just how it is. They will stiffen a bit and work better but they will never be awesome brakes. Just how it is on 99 and earlier Tahoes. Hope it helps. Very important to bleed correctly though. I'll bleed my 83 Toyota 4x4 myself but not the Tahoe.