Hard starting, randomly.
http://shbox.com/1/4th_gen_tech2.html#opti_test
Mine acted very similar - long starting times for about 4 months then Pop! The Opti low res signal (DTC 1371) just died driving down the road, steady, state at 70 MPH. Replace it now before you're stranded!
happened to me to it only gets worse.. noone was a help i just decided to replace it one day and found the old one burnt lookin






