Civic EG

for some odd reason my car won't drive past 4000rpm; it just started happening last week with i was tighten my clutch line to my slave cause it was leaking. The problem don't happen until after driving for about 20mins. It will drive past 4k rpm in the beginning but once it get driving and warmed up it start acting funny. I changed all my fluids...still same problem. so what could be cause this to happen. the car is an 94eg coupe with an d15b vtec swap. your help will be much appreciate. thanks

Is it throwing any codes?

I had a chipped ecu in my del sol and one rainy day I had the same problem I put a stock p28 in it and that solved my problem.

Your ECU went into safe mode. You are throwing a code of some sort. Or it is a vacuum leak somewhere. Check all the vacuum lines.