Do you hear the wooshing from in the car (under the dash)? Has the check engine light come on? Have you checked fuel pump pressure?
Here is a how to for checking pressure. Check it to make sure it is good. Also, if you didn't replace the fuel filter when you tuned it, you may want to consider it.
https://www.2carpros.com/how_to/how_to_check_fuel_pressure.htm
You will need a gauge to check it, but most parts stores will lend or rent them.
Run a back pressure test on the exhaust. It could be a partly blocked exhaust. The 30 seconds is about what it takes for it to light off. Does it use any coolant? oil?
Let me know what you find.
Joe
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Monday, December 21st, 2009 AT 1:04 PM