My 2000 Nissan Sentra has 135,000 miles. I failed emissions and they gave me 3 codes P0180, P0700, P0733, also the service engine light is on. Also when driving there are times when there is no power pressing all the way on the gas, then it kicks in to only hesitate again. This goes on at varying times while driving. Also on the freeway I used to be able to get up to 75 but now it only goes to 55-65 mph then goes down to 50-55 by itself. And I can put it on cruise at 70-75mph and it will kick it self of cruise and go down to 60-65. Any help?