Jay_Z1287

Hi everyone I have a 94 GMC safari and Im kinda stuck here... I replaced the throtle position sensore the idle air control sensore all the vacume hoses checked the intake manifold cause the shop I brought it too said that It could be that and there are no vacume leaks there... I turn the van on and it sounds like its running at around 4000 rpm I dont have a tachometer so I dont know excactly... I also reset the computer a couple of times to see if that would sovle the problem but it still is running high..Somone told me that I could bring it to the dealer and have the idle dropped using the computer. Everytime I do the diagnostic it shows no codes. MY buddy told me that your car can control the idle through the computer so could I goto a dealership and see if they can just reset my settings??? I am at a dead end here and I need help thanks!