I found out last time the coolant temp sensor (the one look like O2 sensor) was loose.But after I fixed it,the problem seems not going away.I also think it's about fuel/air/spark but this happen when it's hot and when the engine at heavy load usually.I change the sparkplug and doesn't solve the problem.My engine is 1st gen JDM B16A with PR3 ECU.The car was running fine for 6 months before this problem start a week ago.Anyone have different opinion? Thanks.