i have a 06 5.9l. my tach jumps from 700rpm to 200rpm with no change in exhaust tone witch leads my to believe its an ecu issue. it does this threw out the rpm range. my tranny seems to be slipping under loads and will kick out of first gear at around 10 to 12 mph. it had never done it before. i have a mbrp exhaust and a k&N intake. i'm out of ideas and need my truck for work, i don't have time to leave it at a dealer. any help is better then nothing.

 

What was the cause, I'm experiencing similar issues.