new motor had roughly 600 miles, it smokes at idle, but not under throttle. ive come to the conclusion the valve guide seals are shot, but within the last 2 days, the car feels like it has like 3 dead cylinders, and if i go to get into the gas theres nothing there then this morning i put it about halfway down and the car just like bogged out and died, i restarted it and it backfired bad!! it also has a tick comming from the engine bay, so as soon as it cools down im gonna check the headers and the plugs to see if they are loose, also the car hits a brick wall at 4800rpm so im guessin the opti is shot to hell too. is there something else i should check?

 

Make sure the valve adjustment is correct. Ya have all the symptoms of valves to tight. Could be plugs and wires also.

 

I had the same issues. Turned out I spun a main and a rod bearing.

 

im hopeing its not a rod bearing. they are all brand new!!

 

mine didn't backfire, but it made ticking/squeeling noises and it wouldn't rev very high and most of the time would cut out when I got on it. Maybe change your oil and look for some metal, but I hope for your sake its not a bearing and is the opti or something else especially since your motor is new.