1999 Hyundai Sonata no power rough run after warm

98,000 miles on Hyundai Sonata. When starting from cold it will run fine. After up to temperature problems start. Sequence to recreate is as follows: start and drive first thing in the morning, drive 1.5 miles to stop sign the car dies. Will not restart unless key is turned completely to the off position. It then will start but will run rough with no power. Can only run 50 MPH and tach will not go over 3000 RPM (not steady either). Drive 1.5 miles home; stop in driveway car does not die. Put in neutral and car will only tach 3000 up to 3500 and back down to 3000 (ramps up and down with no change in throttle position). Turn the key to the off position and restart and the engine will rev up fine but I detect a miss (not bad or consistant). Check engine light is not on. Have not tried to read for codes as of yet. Will the ECU show any codes even if the check engine light is not on? I have obtained from the Hyundai web site the electrical schematics and component location diagrams. Drove to Azone to have code read. On the way there the check engine light came on. Codes are as follows. First one P0335 Followed by P0740. I was able to get the code definitions from the Hyundai site. Thanks for confirming what they say. The Crank shaft position sensor is an easy replacement which I can do with no problem. Will this sensor cause it to run rough enough to give the Torque converter sensor fault. I don't really want to just throw parts at it without a justifiable end to the means. Thanks in advance