Shaking at idle and Hard start when Warm

[BlkExplorerSport]

Hey guys please help me with this because i've been trying to get it answered on here a few times but no one replies. i have a 99 explorer sport SOHC and when i start it the idle is about 500 constant and the inside is shaking like the engine is shaking. it doesn't make any noise but it is so annoying. i want to keep this explorer for a longggggg time but if its giving me problems i dont want it. If i look over to the empty passenger seat its shaking just sitting at an idle or at a stop light. another thing is sometimes when i drive it for a long time. then shut it off and try turn it back on in a few minutes. sometimes it wont start the first time i have no idea why..

please guys help me out i don't want to pay ford to tell me because last time i had to get a new head gasket from ford it costed 800 so please help me out!

 

[BlkExplorerSport]

Anyone ?..

 

[rileyrs]

is it just vibration, or is there also a knocking/ pinging coming from the engine?
if its just shaking, then it could be the engine mounts.
if its a knocking sound, is it at idle only, or is it always there?

 

[BlkExplorerSport]

its vibration and shaking at idle. no knocking or pinging. sometimes when i drive and hit the brake and am sitting i can hear my back glass vibrating like the whole cabin is vibrating

 

[rileyrs]

does it have any vaccum leake..ie does it sound like air is being sucked in somewhere, or after you shut off the truck, is there a sound of air being sucked in?
if so let me know... if not:
first id replace the fuel filter and clean the iac and maf, just incase its a misfire.
also how old are you plugs/wires?

 

[BlkExplorerSport]

i had a vacuum leak and head gaskets replaced and before the car would stall unless i tapped the gas. but i still have shacking / vibrating

 

[rileyrs]

if you have another vac leak somewhere that is more minor, it will cause a rough idle.
when its in park or nuetral, what rpm do you idle at?