K&n Filter problems
So Have a 2001 ranger 4.0 put the K&N fipk system on it. The engine would rev up and then go down to below 500 rpm. sometimes would die sometimes it would come back to around 1000 rpm. It would do it not all the time but it would also happen at random times. replaced the tps two times didnt do anything. So i took it to a shop they cleaned out the MAF and something else took the filter off and put the stock one back on. it has been running ok since. it runs it doesnt hesitate like before, but it still has a rough idle. Any ideas? Class anyone?