I'd start with checking the ECU for error codes. If memory serves me right you need to find your diagnostics box in the engine bay somewhere, shorting pins E1 and T (probably worth searching the forums for exact details as i don't have them handy)
This will spit out any codes that the ECU stored such as a code 31 meaning your airflow meter isn't working.
Chances are there are some error codes stored and will report what the problem is.
Also check all your intake piping for any possible leaks