Toyota Repair: 97 4-runner lacking power, fuel regulator, trouble code

Question
Thank you for responding to my question yesterday.My mechanic used a scantool today to look for codes nothing showed up,which really has him confused. the check engine light was on about a week ago for 2 days then it went off.my mechanic checked today for fuel presssure he said it was enough and maybe even too much and thought it might be a fuel regulator.Any suggestions? Thank you for your time.

Answer
If the check engine light went on and then off there should be a trouble code in either pending codes or codes history on the scantool, was it checked for that?
These engines are prone to misfires caused by bad ignition coil packs, a misfire code would confirm this, if not I would drive it until the engine light came on again to set a hard fault code(remains on)also you should have the catalityc converter performance checked.