I'm hoping someone might have some insight as to what's going on here. https://youtu.be/rhZzZZyLbd4 This is a friend's 2001 Xterra that came in with an intermittent overheating issue. While trying to replicate the overheating issue I noticed that a p0300 (random multiple misfire) would set at rpm above 3 to 3.5k rpm. The p0300 is set as a pending code. However the engine runs fine with no noticeable misfire. Cap rotor and plugs have been done by a previous shop. I also can't seem to replicate the overheating issue. After replacing the thermostat (done by someone else) it overheated twice on him, once while towing and once while driving normal highway miles. the cooling system was flashed a few hundred miles to go with a chemical flush (was likely prestone rad flush) O2 sensors seemed responsive and seem to read from 0.090v to 0.500v at idle and around 0.600v-0.700v when at around 4k rpm. I mention this because maybe it could be an o2 sensor sticking high causing the engine to run lean and overheat? I plan to be doing the water pump and fan clutch soon. am I replacing the right parts?

  • intermittent as only under load ie up hill with a trailer or just odd times in cruise on the flat? Has the radiator been checked? obstructions external or internal, flushed?
    – Solar Mike
    May 7 '19 at 8:35
  • I guess despite rereading my question multiple times I missed some very important parts, sorry May 7 '19 at 8:36
  • After replacing the thermostat it overheated once while towing and once while driving normally on the highway. The cooling system was flushed some hundred miles ago with a chemical flush, apologies for 2 comments. I thought you could put a line break in a comment May 7 '19 at 8:36
  • update your original question with that info, also some formatting will make it easier to read.
    – Solar Mike
    May 7 '19 at 8:39
  • See this post as well : mechanics.stackexchange.com/q/67033/10976
    – Solar Mike
    May 8 '19 at 5:54

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