Help with codes

[NJFord]

Hooked up to the OBD and I am pulling codes P0300,0301,0302,0303 for misfires in #s 1, 2 & 3. Also pulling 0316 for misfire during startup, 0171 and 0174 for system too lean (bank 1 & 2). I threw in some Rislone and ran Seafoam through the vacume line as I have read that is a good start but still having problems. Here's what I am experiencing. When I start up, the engine runs a little ruff but does not seem like I am misfireing. After a minute or so, I start getting a serious taping in the valve cover on the passanger side of the engine. It gets a little louder and I can tell the speed of the "tapping" is keeping time with the revs (faster at higher rpms) If I let it sit for a few hours, it will start without tapping again but sure enough it will start again in a minute or two. Kinda at a loss and don't want to start buying parts that aren't necessary as times are real tuff right now (NYC construction worker waiting on Union assignment for almost a year) Any ideas would be extremely appriciated.
2003 sport trac 4.0 (not the flex) with about 110 K miles on it.

 

[NJFord]

Was able to clear out the 071 and 074 codes with a new PCV hose... The elbow had collapsed. Still getting the 0300 > 0303 and the 0316.... Any help would be greatly appreciated....

 

[NJFord]

Update... Took off timing cover and the tensioner for the crank shaft to jack shaft was busted.... Plastic in a few pieces... Leaf springs out of place. So it's back together and the I was getting a P0122 code.... So I threw in a new TPS and thought I was code free until I got hit with the P0172 (rich bank 1) so I just pulled my MAF and shot it with the cleaner. Will throw it in tomorrow but don't have much hope as I think if it was MAF I would be rich in bank 2 also... Any ideas? Please help.... Been pulling codes, fixing codes and getting new codes for over a week now