engine idle is rough

['88 5FOX]

I am new to this site and think I am in the right place to be asking questions.
I have a 88 fox that I converted the trans to a 5 speed, and slid another motor down in. Last week it was running fine. I had two injectors leaking so I replaced all of them, now I have no leaks. But I installed 24lb injectors in on a speed density system. Found out that wouldn't work and installed a mass air system on it hoping to fix it. It didn't and now it will run but idle's like there is a vacuum loose although I have thourghly checked all of them. It throws black smoke when I step on it and from what idle I do have if I step on it it will studder out at around 3500 and kicks black smoke everywhere. When I unplug the mass air it doesn't affect the idle one bit. I have even checked it with a known good sensor and the tps. Timing is also set at factory specs. Neither fixed the problem. I don't want to blow my spark plugs out while driving. Can anyone give me a hand on what I should try next.

 

[jrichker]

You posted a TECH question in Talk. This limits your chances of getting some really good advice, since most guys aren't looking for Tech stuff in the Talk forum. PM one of the Mods (85ragtop, Killercanary, Mustang5L5, Celeb, FrankenStang, FastDriver ) and ask them to move it to 5.0 Tech. You’ll get a lot more responses to your question.

Having said that, here’s some help…

When you use lager injectors you need a aftermarket MAF calibrated to match the injectors or a custom computer tune. Until you fix that problem, you are going to have performance/driveablity issues.

Stock injectors are 19 LB orange or tan tops. You don't need 24 LB injectors on a stock engine,

 

[NIKwoaC]

You posted a TECH question in Talk. This limits your chances of getting some really good advice, since most guys aren't looking for Tech stuff in the Talk forum. PM one of the Mods (85ragtop, Killercanary, Mustang5L5, Celeb, FrankenStang, FastDriver ) and ask them to move it to 5.0 Tech. You’ll get a lot more responses to your question.

Having said that, here’s some help…

When you use lager injectors you need a aftermarket MAF calibrated to match the injectors or a custom computer tune. Until you fix that problem, you are going to have performance/driveablity issues.

Stock injectors are 19 LB orange or tan tops. You don't need 24 LB injectors on a stock engine,

Everything he said.

 

[Mustang5L5]

Moved to tech.


Get a calibrated maf on there and then dump the check engine codes