Hyundai Repair: Hyndai Sonata 2002 Malfunction Indicator Light, malfunction indicator light, transmission control module

Question
Malfunction Indicator light came on today and car is having difficulty negotiating heights, though drove normally on horizontal stretch (40 kms) with Malfunction Indicator light on all the time.  

Answer
Start by checking your trouble codes in the engine control module (ECM) and transmission control module (TCM).  This will likely give you information about the exact cause of your symptoms.  AutoZone and AAMCO have advertised they'll read your trouble codes at no charge.  Once you have the codes, follow-up with the code numbers.  I'll tell you what they mean and advise you on how to proceed with diagnosis/repair.