i own a 1995 deville with the 4.9 it has 127000 miles on it and has some trouble... from reviewing this site i know that i have to purchase an isc motor... but the real problem is my check engine light. it never turns on in town but when i hit the freeway it comes on after five minutes. i recently had the transmission rebuilt. i dont know if its overheating or what. i live in flagstaff arizona and used to take it on frequent trips to phoenix. now i am afraid that my beloved caddy wont make it anymore. i havent had the time to run the trouble code because the light turns off after shut down and restarting.....help!