Car shuts off after 15 min
 

Hi everyone I really need help so my rx8 littirally wouldnt iddle before so I went crazy I have changed the plugs coils leads o2 sensors got upgraded starter motor so now I can get the car started from cold and it iddles perfectly for about 8 min then stwrts to drop to 800rpm amd picking itself up and all of the suden within few rpm drops and pick ups it will pick up and then just drop and die but this usuqlly happens when the car is on operating temperature fans dont come on or anything which im guessing it means it isnt overheating but when it cuts out it dosent want to start untill its cold again Iwould say oh seals are gone but the engine has been rebuilt around 15k miles ago so no Iim really stuck and I dont know whats wrong I have no codes comming up but before I did have the crankshaft sensor come up but now its gone could it be that the sensor is overheating and failing or could it be the fuel pump if anyone has any ideas please help me cause ive put in allot of money so I dont really want to spend more any help will be much appreciated

How about some punctuation and sentence structure that makes what you typed readable?

start with a compression test, something could of went wrong with the build. Sounds like bad compression to me. Mine did the same thing before I needed a new engine.

you know what I always check first when my car decides to die like that? Battery and alternator and fuses/circuits first. Especially since you have no codes throwing. Then I check fuel, spark, and air. Then I shell out money for those expensive diagnostics. But it's always a good idea to maybe clean and reset your computer. My vehicle did exactly like you are talking about but had a bad battery cell. Easy fix.

Occam's razor- "It states that among competing hypotheses, the one with the fewest assumptions should be selected. Other, more complicated solutions may ultimately prove correct, but—in the absence of certainty—the fewer assumptions that are made, the better."

With all you changed, did you 20 brake stomp or leave the battery disconnected for half an hour or so?

Sounds like the ECU needs to figure out the changes. I suggest the ECU reset of choice then start the car COLD. Let it idle until is it is nice and smooth. when it gets to the lower RPM, you might have to help, but turning on the AC will usually bump the idle enough to take care of it.

I've reset the ecu I turn the ac on and idle drops but picks itself back up its literally 10-15 minutes all the time and the car just shuts down battery and alternator are fine I'm really confused and after it dies it won't start back up until like an hour Btw power steering came back aswell randomly