97 f150 168000 starts won't idle plus heavy white smoke should i shoot it? happend suddenly oil level good ,cleaned IAC&EGR no vac leaks, possible plugs ?.its been awhile scence changed.no check engine light.giving it lite petal[gas] helps very little,still dies.

 

How is the antifreeze level? Is this a 4.2 V6? Head gasket....

 

4.6 v8 5spd extracab 4x4antifreeze seem ok i'll double check for oil in it,no "milk"on dipstick

 

x2 on possible head gasket failure.

Don't always get antifreeze into the oil if the gasket fails. Check your fluid levels closely.

 

the oil level has raised above the full level on dipstick. does anyone know approx. cost for repair? if head gasket is blown.how do I confrim its the gasket? could it be the casting"freeze plugs"behind timing cover.Again NO"milk"on dipstick just high level on stick,won't idle and white smoke@tailpipe

 

Crawl under the truck, slowly back out the oil drain plug, and, if there is any coolant in there, you will see it slowly walk down the threads. I am guessing with the "ABOVE FULL" oil level, you have a blown head gasket and the coolant is seeping into your oil. We will go that route first. That is the easiest way to tell if the gasket is blown. (well, besides the visuals you are getting)
I had a 1980 351M do the same thing, and, ended up cracking the block in the meantime. DO NOT RUN THIS MOTOR! IMO!