Greetings all! The truck mentioned is a 99 Ram 1500, 2wd, 318 engine,
and here is the problem:

When cruizing down the highway and the cruise control is set (between
50-70 mph), the engine will "surge". By "surge", I mean the tach will
suddenly rev 200 rpm and come back down.  I am thinking the Lock-up
torque converter is kicking in and out. It rarely "surges" when the
cruise control is OFF, although it will do it on very cold days. PROBLEM
TWO: After the truck has sat overnight and gotten completely cold, I can
leave my driveway and be in overdrive about 1/4 mile away from my house,
even when it is 10 degrees outside. I don't think this is normal as
every other Chrysler trans I have had didn't hit top gear until the
motor had warmed up some. Is this an issue with the transmission fluid
temp sensor, or something else. I have taken the truck to a trans shop
and they found nothing; no fault codes or anything recorded in the PCM.
Has anyone else had this issue? I ask because a friend of mine has a
2000 dakota 3.9 and it does the exact same thing. I haven't had a
mechanic hook a scan tool up yet to monitor the trans fluid temp sensor
readings as I thought if it didn't work it would throw a code. Any
thoughts???

Thanks for your help!!
Nick