...and then it runs perfect. My 91 Ford F150 5.0 FI acts weird when started cold. I have noticed it has gotten worse as the outside temperature has gotten lower. When I first start it the motor sounds like it has a huge cam in it and will barely stay running. I find if I give it a little throttle to bring the R's up to about 2300rpm it smooths out and prevents the engine from shaking itself to death. This lasts 10 seconds at most and then begins to run smooth as silk. It only happens when the truck is cold. While this is doing this you can smell the raw fuel that is being dumped into the engine. While it sounds cool as hell, I know this is not good for it so i would like to figure it out. Any helpful suggestions is appreciated. I did try searching for this prior to asking btw but that didnt net me the answer I was looking for. Thanks ahead of time.

 

Not exactly an answer, but my work Explorer had the EXACT same problem. Different engine (4.0 V6), but the exact same problem.

On the bright side it never got worse, it was just something I dealt with.

Check and see where your oil pressure is reading on the gauge. I always blamed it on a faulty gauge, but my oil pressure always read 0 during those first 10 seconds. If yours does the same, maybe we're catching on to something.

 

Sounds like your Idle Air Control (IAC) is sticking...it's about 70 bucks brand new from the parts store but I'd try pulling it off and apart and cleaning it with carb cleaner.

 

agree, sounds like the Idle Air Control valve, mine did that for years. most time id turn it off then restart it and it would be fine. i replace the iac couple months back and its been fine.

 

Thanks guys, I will try that tonight afterwork.

 

check out ebay, I got myself a new IAC for $35.