When I first start my car in the morning, it does not want to shift from P to R. Once it does it, then I do not have a problem for the rest of the day.

I have tried letting it warm up some, it does not seem to help.
Sometimes if I pump the brake pedal it will do it, but sometimes not.
Sometimes it works after I active several times the OD switch (on this car the OD solenoid is disconnected and the OD solenoid valve has been machined to give me the 4th gear all the time).
I have checked the ATF fluid level (looks good)
I have checked the brake fluid level (about 1/3 above the minimum mark). I think I am going to top it off today. The last time the brake fluid was replaced was in 04/03 (a little less than 2 years ago, about 20 000 miles). I may go ahead and replace it.
I have checked for leaks around the master cylinder and the booster and cannot se any (of course it could be internal).

In summary, has anyone experienced the same thing? Where should I start troubleshooting?

Thanks, everytime I used this forum I got good advice and was able to fix my car.