Hello I own a 04 Built Lightning, Look to see that it Does Not have a J code Trans, Ask if it has the Updated Intercooler ( All 99-2000's) Leaked and should have been up dated Check for a lower Pulley (Blower) Stock or over driven,Has it been tuned and by Who what is the Air Fuel Ratio, Go to Lightning Rodder.com and search this truck by Vin Number, Good Luck Lurch