300zx turning over but wont fire

[tokteza]

Hello all new here but I'm having some trouble.
my Z has been running just fine until yesterday. I was driving for about an hour got onto the highway and she seemed to be a little groggy around 3000rpms felt like a gust of wind would hit it every once and a while. when I drove back it ran just fine?????. Then later that night I drove it ran for about 10 mins and then it flat out died. when I put the key into the second position the battery and brake light are on constant but my battery is brand new and my ALT is only about 2 years old. my fuel pump kicks on and iv tested the pressure. iv checked all the fuses and tested the CAS all is working fine but it still will not fire or even try to. any ideas?

she also throws a code 55 so no trouble there.

[LEMHEAD16]

Check for spark.

An engine needs 4 things to run Fuel, air, compression, and spark. Figure out which one is missing and then you can narrow it down to the sub-system that is malfunctioning.