A customer of mine has a 93 f150 302 with mass air, he had put a 351 in it and it ran fine, he then installed a comp roller cam(a little bigger than an E) and installed edelbrock heads/intake and it searches at idle. Where should he start????

also its the factory mass air setup used on '94 302 trucks

 

That set up is making the computer crazy. Try the idle relearn thing for the MAF? How long has it been running with the set up? It may just need a little run time for the comp to learn.

 

My reply is more based on the theroy of how the system works vs what you have in fact.
The 351 is now being run by a 5L control system.
The air meter is not calibrated to the engine size and extra air intaken at idle. This changes the voltage tranfer curve the EEC is given ie fuel injected..
Have you done the IAC test for idle and throttle body opening check/adjustment? These are critical checks to see what you have.
Next, after all is known and addressed and you still have a problem, a special air bypass plate with it's air adjustments may help due to the cam that may have substantial valve overlap adding to rough idle.
For this situation the EEC can't get a hold of the idle and keeps hunting (swinging the IAC in a chase).
I know it's a lot to try to understand but I don't know any other way to address this for you.
The plate option was a factory part. It goes between the IAC and the intake manifold. It alters the air bypass control so the IAC will hunt less. Somewhat commonly done on Mustangs and at the dealer, at times.
To do the IAC and TB check, fully warm the engine. Remove the IAC connector while the engine is running. Does the engine drop down in idle speed or stall? If yes, raise the idle stop just enough to allow the engine to idle, then reconnect the IAC. Does the engine idle rise? If yes the IAC is working. If no, then there is a problem to find.

If idle is hunting after these checks, you may need the opional plate.

The other thing that gets into the hunting game as well is the vaccum to the fuel regulator swings as the idle changes and affects the fuel pressure to the injectors. This does not help the hunting situation either..

 

Good post! Same thing i said, only with more words.
He may end up taking it to a good tuner with a dyno to get the air/fuel ratio dialed in, along with a re-calibrated MAF meter, and maybe even a reflash on the EEC. This will give him the best bang from the head/cam/intake set up. Not only will this clear up the idle problem, but also utilize the available horsepower.

 

With those mods, things are getting pretty serious. This is what I would do....

-Upgrade the fuel pump and injectors. Consider maybe even running a new in-tank pick-up, larger fuel lines, larger fuel rails, and high-volume in-line pump.
-Adjustable pressure regulator.
-Pick a new large-bore MAF.
-Also a new throttle body.
-Probably want to look for a good A/F gauge too.

Get on the phone and start calling speed shops anywhere near you, or even large cities within driving distance, you want to find one who's an SCT dealer and has a chassis dyno in house. Take the truck to them. Buy a chip from them and have them burn you a custom tune on the dyno. For your friend, the SCT Eliminator Switch Chip would be perfect. They can hold up to 5 custom tunes, so he can have *****-out performance, towing, economy, etc.

Companies like Troyer are great, don't get me wrong, but you will NEVER get as good of a tune as you will with a good tech and a dyno PERIOD! All my tunes are done that way, even my 1200hp TurboStang with F.A.S.T. engine management. That way, even on the race car, I always have a SOLID and SAFE place to work from.