He's having all my new issues since i changed my PCV valve... does it lose the surge if you ever so lightly apply just enough pressure to add tension to your throttle cable? does it have almost a stale fuel smell when it's surging? I am tore between it being a dirty throttle body and a crap-tacular fuel pump....today's project lol
EDIT: May also be my cat's now I guess... talked to a friend and did some reading, my stale smell may just be the foul cat's restricting the exhaust...

 

i'm having the same problem on my 1999 f150 4x4 (po171 and po174 bank 1 and 2). had a vacuum leak on the iacv (idle air control valve and a small rubber line under the plastic cover (toward the end of the air intake hose, i think ). unfortunately, this did not solve the problem. gonna try the fuel pump test next. doesn't seem to have a leak at the exhaust manifold or intake manifold...but who knows...will let yall know..maybe the above info i gave helps someone else..thanks..good luck..

 

Have you replaced the idle air controller? I had the P0300 and P0176 codes a couple of months ago. Same problem, really rough idle below about 43 degrees outside temp, on a couple of really cold mornings it actually died, but not until I had already driven about 3 - 4 miles. Anyway, replacing the IAC worked. I did learn the hard way to stick with Motorcraft when replacing this part, aftermarket ones appear to have some problems.