my engine light blinks when push the gas pedal, it doesnt idle right when idling..sounds like its trying to breath..ive been using octane 91 for a long time now..what do u think is the problem?

that means ur truck is misfiring and it is damaging the catalytic converter get codes pulled from autozone and that will tell u which cyl (s) r missing then pull coil packs on those cylinders to see if u get spark if good solid blue spark than listen to the injector if they r opening then pull the plugs and look at them to see if they are still good if not then replace

i would check the plugs first its eazy

I took it to dealer, they replace the oxygen sensor, engine light shut off for a week, now its doing the same thing..engine light blinking..

You have a misfire, you need to have your ignition system checked out.

Mine did the same.... computor gave a random misfire, after new plugs, wires and O2 sensor at one shop, another shop determined it was the egr valve, this solved the issue. Very easy to replace yourself in 5 minutes, $150.00 part at Napa

Yes, that was what had happen.. been running great ever since, thanks