Cadillac Repair: racing idle/fuel inj., throttle position sensor, intake manifold gasket

Question
I know this is not your make but the top brass suggested I try another expert because the guy in Plymouth was not responding. The problem is new to me. My first fuel injection system. Maybe you have an idea.
   My 88 ply, reliant was running so rough I could not drive it. I checked the codes and it said my automatic idle sensor had a short. I replaced the ais and found the the wire harness was shorted due to heat. Respiced the wires. Then the car idled so high I could not safely drive it. Tried letting it run so the computer could relearn the mix but it never lowered. I rechecked the codes and I still had the asi code coming up, but a new one added to it. The tps--throttle position sensor.I put in a new tps but it changed nothing. The butterfly in the throttle body is fully closed. I can not find any vacuum leaks of any significance--vacuum purge seloid should not cause a racing idle. Can you suggest anything?

Answer
Hi Jim, This Problem is new to me too but here are some things to try. Double check that you spliced the wires correctly. Then disconnect the battery for 5 minuits with the key off and then hook the battery back up and start the engine to see how it runs. If still high then you will need a scan tool to see what the computor sensors are reading and maybe one is way off due to another shorted wire somewhere. If this engine has an upper intake manifold plenum that is part of the cylinder head and under a valve cover you could have an intake manifold gasket leak. To check this remove the hose comming from the air filter housing and block the air from going into the engine. If it dies then there arn't any leaks but if it continues to run there is an air leak somewhere that needs to be fixed. You could take the car in and have it diagnosed and then do the work or have them do it. Problems like this stump even the best of us from time to time. Good luck. Bill