slammin-95-chevy

hi i have a 1995 chevy c1500 i just recently put a motor in it the motor that i put in was out of a 94 blazer it has 110,000 miles on it. well it went in verry easy and and had no probs now i have it running but it stutters between 1,000 and 2,000 rpms. so i figure its the sparkplugs so i changed them still does it but under the hood on the top left side of the motor there is a vacum madual that is hoock up from the intake to the egr valve. when i umplug it the motor doesnt do it anymore. but i plug it back in and it does it so i changed it. now its still doing it i cheked the egr valve and its good. any sugjestion or other things i can chek.

thanks for your help oh and im new to this forum