94 limited Rattling problems

[Fordman6996]

hello,
I have a 94 limted 4.0 V6 my problem is I hear a rattleing sound from under the car while its Idleing I crawled under the car while it was running thinking it was the exhaust shields on the converters but there broken off, and I didn't hear anything from the converters I can't seem to pin point the source where its coming from you can also hear it while I'm driving down the interstate at about 75 mph and if I give it gas it gets louder to a point then quiets but the faster I go the louder it gets I know its not any suspension problems I know its a engine problem my friend at work thought it might be some thing called a heat idler valve but I don't know if I have one he said it will branch off of the smog pump, I looked under my car and I didn't see a smog pump just alternator power stearing idler pulley and tension pulley crank pully A/C pulley and water pump pulley. or would it be the EGR Valve? but the sound seems to come from under the car, I'm just frustraited about it sounds like the main bearings are going to lock up,

My other problem is when I start my car it runs fine besides the rattling sound then after it gets warm and I shut it off then go to start it 5 to 10 mins later it idles really rough and if I rev it a couple times or get it on the road and drive it comes out of it? please some one help me I've taken it to the Ford dealership twice and they said it runs fine. I've also replaced the mass air flow sensor. if some one has some answers I would appreciated it!

 

[southtxexplorer]

It is a long shot, but I had a persistent rattling sound under mine. I checked all the heat shields which all seemed to be secure. Finally, I noticed a tiny rock in one of the drain holes on one of the shields. The rock was not lodged in the whole, but just resting about half-way in drain whole. The rock was tiny, but it made an incredable racket, especially at idle. Like I said, its a long shot.

 

[Fordman6996]

:exp:
on my X all the heat shields are removed but I know what your talking about cause that used to happen alot till I took them off Haven't had the re welded back on so I know its not that.

 

[TPLYNCH]

could be the bearings in one of the pullys or the waterpump. Sure it's not the exhaust pipe itself rattling? Make sure the whole thing is tight and you don't have a loose hanger etc.