I got the esc in a trade. It's like new and wasn't actually run in a car bfore i got it. I hooked it up and calibrated it and set everything where i wanted it with the program card..hooked it up with a savox 1258, and a tacon 3660 3500kv motor..with a spektrum radio system.used a 5800mah 65c 2s lipo .very 1st time i drove the truck..it was missing a rear driveshaft..but the esc worked good..only drove it for about 2-3 minutes..went forward fine..backwards fine..brakes worked...so i got my other driveshaft in and fired it up again..this time when i turned the wheels left or right, the servo glitched and returned the wheels to center position..every time i turned and hit the throttle it did this. also when i put it in reverse and let off throttle...the car would keep going 3 -4 foot bfore it would stop..then, i swapped servos to a cheap rtr servo and tried again..this time it did the same thing with the steering..cutting out and returning to center..and reverse did the same thing, kept going aftr i let off the throttle..and now when i try to go forward, if i stay under 1/4 throttle, it will turn fine and drive fine...but if i go over 1/4 throttle, the truck cuts out with the steering and the throttle..it'll go and stop, go and stop, go and stop...i tried recalibrating the esc, and all my radio settings are like the book says to have them...not sure what to do..is the esc bad?? it's literally brand new..only like 5 minutes on it..I don't understand why it worked great when i was missing a driveshaft..and now that all wheels are hooked up it's messing up??

Well, we know an extra driveshaft cant directly affect the electronics, so I would suspect some type of silly error somewhere. It is possible the ESC or some other electronics component has failed since the first run, but not very likely unless it was stressed its first run or connected improperly at some point. If you are certain all of your connections are secure, radio settings are correct and the calibration is done properly, the only way to know for sure is to replace the ESC/servo/receiver with a known-good unit one at a time until the problem goes away.

Rarely, some radios will seem to calibrate properly but have trouble similar to yours anyways. It may be worth trying a few things before you condemn any particular parts. One trick is to calibrate with the radio at max EPA, then try backing off 1-5%. Another is just the opposite, calibrate at a little less than max EPA, then turn it up a few extra degrees. I am not certain if some radios can "overextend" the throttle range or what, but I have seen this work in some cases.
Using the ESC programming card, I would recommend starting with the largest deadband (neutral range) setting, if you get clean and smooth operation you can increase this for better response. However, some radios "drift" a bit right around neutral and can cause some of the issues you described if the range is not high enough. Finally, I would suggest testing the truck in a wide open space where you can unplug the steering servo and check throttle operation. If you get normal operation with the servo not connected it may very well be a faulty or weak BEC in the ESC causing the erratic operation.

It's a known problem with the 80 amp hobbywings they don't like 2 cells without a external bec. if you put a bec on it it will work fine.

that's what i've been leaning towards doing..do you think if i did the spektrum rx mod and put a cap in the rx it would work? would it hurt to have the bec and a cap in the rx??

I'd add the cap first and see what happens, alot cheaper and easier to add a cap than do a bec.