Where are you located. Expericed a r31 skyline with 1g beams engine was very smooth and sounded good. Missing could be many reasons. Distributor, fuel pressure, plugs, map, etc. You should check if you have good fuel pressure by cranking it while taking apart the fuel line. You should check if all plugs have spark ( take apart plug wires one by one while engine is running and putting it near and metal part like head and seeing if there's spark, this is if it's a 1gfe with distributor ) Agay phir mechanic ya electricatian hell Kar sakta