my 92 5.0L f150 cranks real fast, but sometimes has issues. bogs after it starts firing. it never dies and it always runs after, but just worried if its a symptom of something that will be expensive. only does it randomly too. on cold starts it works fine as well as hot starts.

 

Cranks real fast, but does it crank unevenly like some of the cylinders have less compression than others?

You can do a compression test or put a vacuum gauge on it while it's running if you want an idea of what shape it's in.

 

it has decent compression for a '92 302. it burns and sounds clean and smooth. tailpipes can be cleaned shiny new with soap and a rag hah. for awhile it was idling rough, but i cleaned the connections on the distributor cap and it cleared that up. any specific place to get a vacuum test done? or is it possible to do it yourself?

 

You do it yourself by renting or buying a vacuum gauge (they are cheap) and connecting it to the vacuum tree on the intake.

Then look here: How to Use and Interpret a Vacuum Gauge

It mentions carburetors but it don't matter. About 3/4 of the way down the page is an animation that shows different things you might see on your gauge along with the cause of each one.

AutoZone might rent you a vacuum gauge (I say might because I don't know if that's something in their rental inventory) and if not they have them there for like $25. Harbor Freight has one for about $10 less if you have a store near you.

 

easy enough. i got autozone, aTi autoparts, Napa, and o'riellys.

 

And if your vacuum readings look good, I would check fuel pressure next.

Also wouldn't hurt to check the computer for fault codes. These can be present even if your engine light ain't on and is usually recommended as the first thing to do, but since the hard start and fast cranking problems both appeared together at the same time, I'd start with checking vacuum first.