Oldsmobile/Buick Repair: ROUGH IDLE, throttlebody, hi way

Question
I HAVE A 88 CUTLASS CEIRA 2.8 AND WHEN YOU START IT UP IT WILL IDLE UP HIGH AND GO BACK DOWN A FEW SECONDS LATER. WHEN IT RUN FOR ABOUT 5 MINS. IT STARTS TO BOGG DOWN AND IDLE UP. IT DOES THIS FOR ABOUT 2 MINS AND STARTS TO IDLE PROPERLY FOR ABOUT 5 MINS AND ACTS UP AGAIN. I CHANGED PLUGS AND WIRES, CAP AND BUTTON AND STILL NO LUCK RUNNING OUT OF OPTIONS. I DONT WANT TO JUNK CAR BECAUSE RUNS LIKE A CHAMP ON THE HI-WAY. IF YOU GET A MOMENT TO THINK ABOUT IT AND KNOW SOMETHING ABOUT THIS PROBLEM THAT I DONT KNOW PLEASE EMAIL ME AND CLUE ME IN. THANK YOU


Answer
hi dale,, sounds like a bad iac motor {idle air control} this part is on the throttlebody where the accel cable hooks .it is a black sensor and it will have a wide flat plug on it.or possibly a large round plug depending on which is on your car.this is normally the prob .but before you change this with eng idleing tap on egr valve see if this changes anything if yes valve is bad.check real good for a vacum leak manafold gasket or throttlebody .good luck hope this helps please vote for me billymac