If the reason for replacing the water pump was due to overheating, you might have already damaged the head gakets before the replacement.
Check if the cooling system has been properly bled of air.
As to the sluggish acceleration, most probably the tiiming belt has been installed incorrectly resulting in the cam timings out of position. Recheck the timing marks to confirm.
Tuesday, December 22nd, 2009 AT 11:08 AM