Ok, got restricted performance now and again a few weeks back,did a hard reset and everything ran fine for about 4days,discovered battery to be 8years old so I perches a new battery,everything perfect for 3weeks now it's happening again,also got engine warning light but that went off when I opened the fuel cap,go figure? What to try next guys any ideas, thanks.

 

As the mantra goes you will need to try and capture the codes, also putting your MY in signature will help to know what year / make you have.

 

Check actual voltages (may be bad cable / connection / alternator).

 

Get a fault code reader & take it from there.