My daughter's re-rebuilt (by me) 242 turbo intercooler is put put put with little or no power. I am a fairly decent follow the directions type mechanic and can fix most things if given good input from those "in the know." My problem is that this 242ti was running fine the other day until about 15 minutes down the highway and then it started running real rough. My daughter brought it home and I changed the plugs and it made a difference, for about 15 minutes again, and started running rough again. I changed the timing belt last summer and timed it. For it to do this now is strange. The turbo starts singing earlier and with less power than it used to and I wonder if it may be the problem. I plan on re-checking the timing and belt and replacing plugs, spark wires, cap and rotor with all Bosch. I do not think there is a leak in the intercooler or hoses and vacuum lines seem ok. I wonder if once the turbo gets real hot it starts the problem. It actually runs like it has only three cylinders firing. Putputput. Any ideas?