Hello, I recently have been getting OBD codes p0171 and p0174(lean both banks) along with a few other vacuum related problems. I suspected that the cause is a faulty lower intake gasket. However, I wanted to explore the symptoms further before tearing into the engine so, I bought a OBDII tool with live data so that I could see fuel trim data. Here is the problem, all of the fuel trim parameters read -100% and never change. I have tried the scan tool on other vehicles and have no problems reading any live data parameter so the tool is working properly. I thought all 1996+ vehicles supported live data. am I wrong? Or is my computer doing something odd?