QuestionQUESTION: This is a 4.6L Northstar. When it has been sitting for more than 8 hours, it starts perfectly. If I drive to work and try to start it 2-4 hours later, I have to hold the key down and listen to it crank for about 3-5 seconds and then it'll turn over. When it finally does, the RPM's creep from 500 up to 1000 and then the idle is fine. Even at it's worst start, no engine light. Also, while I'm driving and I'm just mainting speed with just a little pressure on the gas, it jerks slightly as if it can't tell if I'm applying gas or not. Overall, heavy acceleration, high speed driving and idling are fine.
ANSWER: Could be an intermittent TPS sensor and or most likely a residue buildup within the throttle body and on both side of the throttle plate as well as a residue buildup within the EGR passages that needs to be cleaned.
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QUESTION: Ok, I've already been in both those areas. I replaced the TPS a month ago with no difference in symptoms. The EGR threw a code and I replaced that 2 weeks ago. You mentioned EGR passages. Are those in the unit itself, which is brand new now, or the in the tunnels leading to the exhaust?
Answermost likely a residue buildup within the throttle body and on both side of the throttle plate as well as a residue buildup within the EGR passages of the engine that needs to be cleaned.
Look down the throttl;e plate area and see all the blackish residue that you need to clean off with an aerosol cleaner.
