I have a 99 dodge ram 1500 v6,the rpms go high before shifting into 2nd sometimes,if start out slow it usually shifts ok but not always,mostly not

Have you checked for a broken valve spring. Repaired a dodge engine with the same running issue as you have described and it was a broken intake valve spring.

I have a 1998 ram 1500. And sometines especially when its hot outside mine down shifts hard as I'm slowing down. And the gas pedal feels stiff. I press the gas down real fast and it unsticks but then when I come to the next light it does it again. If it's cold out dose it doesn't do it as much if at all. I heard it could be a throttle body sensor. Any advise?

It wouldnt be the spark plugs.. It would be doing it all the time if you had a mis-fire. It sounds more like your torque convertor going bad, or your shift solenoid.

Try some tranX. My transmission would drop out from 2nd and 3rd , I put this in and with in 3 days it quit slipping. and shifted normally. It's been over 2 years now without a problem

trans needs fluid or is going bad

have you dropped the pan to see whats the bands are set at, any debris in pan bottom, whats your governor pressure, if bands are ok, but gov pressures are not relative to speed 1 psi per mph up to 95-127psi, port is on pass side of case rear top right, scan tool would be very helpful, your must have mil light on for this problem, gov dtc's, replace gov transducer as gov solniod as a pair, no exceptions, also are there any 02 sensor dtc's, shorted to voltage, this wil make pcm do stupid things to trans shift, affecting gov signals. GOOD LUCK RDJRP

sounds like trans has gone bad, last service of filter and fluid? clogged screen or low/burnt fluid would effest but if clunking sounds like trans is shot

Have you changed the fluid and filter every 2 yrs or 36k miles?
Are you using atf+4 only?
If all the above are a yes then check the throttle cable to the transmission as it should be adjusted to move at exactly the same as the throttle and it they are out of adjustment the transmission will not shift at the correct time and wil eventually cause early failure,also after a rebuild the tranny has to be reflashed by a dealer

I had the same problem with my 96 Ram 1500. I thought I was going to have to pull it out and get it rebuilt or just replace it. That was at 134,000Km it's now got 210,000 and shifting like a dream. What I did to solve the problem was this, as follows:
1. No lucas transmission Fix makes things worse.
2. Get your self a new transmission filter and gasket
3. Grab Gunk transmission medic 12oz
4. Grab 7 Liters of Valvoline ATF+4 transmission fluid (Made for chrysler transmissions)
5. Drop the trans pan and drain all the oil, clean pan and magnet
6. start truck for 5 seconds and the pump will pour out another 1 liter
7. re-install filter, gasket and pan, then add your Valvoline ATF+4
8. Add, the valvoline, transmission medic and make sure you have the right level of fluid

That solved my transmission problems, instantly it was shifting better, I no longer had to let off the gas to make it shift. Now if you have large pieces of metal on the magnet, and it's totally covered in filings, you might want to consider rebuilding the trans. My magnet had usual clutch.         

Anyhow good luck, let me know if it did the trick for you.
Justin