if it feels like its not running quite right even after service with new spark plugs, fuel filter and fresh tank of 98 ran through it i would start looking into it abit deeper .
Each engine has the ecu calibrated to suit, so may need a tune to get the full potential of the new engine! would be interesting to know if its running on the 1.8 ECU or the 2Ls one. i have seen the programming for the 1.8 and 2L side by side and they are similar enough that it would probably run, but would have hiccups here and there and not be as powerful as it should be.