Bad programming or bad computer?

I installed a 98 vortec 5.7L in my 92 GMC pickup and had a shop out of my area build me a wiring harness and program my computer to work in my truck.The truck runs great i am very pleased with one exception.On ocassion after a warm restart the truck slowly builds to the idle rpm that was programmed which the shop tells me is 700 rpm at idle.Also the main problem is that when the a/c compressor is engaged the computer does not compensate for the a/c request it draws down the engine and IAC counts do not increase to compensate.Also when the a/c compressor cycles even driving 65mph the truck will buck slightly when it occurs.This is a big problem in my area where we run a/c most of the year(Arizona enough said 110 for months).After contacting the shop that did the work and waiting for more than two weeks for a response they tell me that there is nothing that they could have done in the programming that would take away the ability for the computer to compensate for a/c and that it may be a bad computer.I do not know for sure that the computer worked prior because it was bought off a parted out truck but have not seen this bad on one of these computers.They used Ls1 edit to do the programming on this computer and i am posting to see if any of the experts on this board can help me out cause i feel stuck and can not get answers from the shop that did the work.Help would be very much appreciated and i will return the favor if anyone has any differential or driveshaft questions i have been in this buisness for 16 years and would be glad to help. Thanks

I would suggest getting the idle turned up to about 850 or higher, makes the a/c more efficient and the alternator not work so hard to give your blower and/or radiator fans more power.