I have a 93 Ford F-250 460 4x4 that I bought a couple months ago. It ran fine for about a month and then the check engine light started coming on and it runs rough and hard shifts. At first it just came in every now and then but is on constant now. Checked vac lines they all seem good. Erg valve or map? Could one be setting off both codes? I am getting codes 126, 334, and now recently 452. Could map sensor be the cause of all codes? Could 452 be caused by driving it with the other codes?

 

One thing you might check and that is to check voltages at each of the components MAP,, EGR and DPFE sensors and speed sensor..
One of them may be shorted and pulling down the voltage to the others.
You can check the voltage at one of them with the others disconnected and watch what hap[pens when you reconnect them one at a time.
Does vehicle have 4.9 engine or a different one?
The DPFE sensor was the most troublesome one.