Engine rebuild running rough. Options

[BondedBlowfish]

Having a hard time getting this thing to run so I'm resorting to the help of others.

Just finished a 5sfe engine rebuild and I'm having a hard time getting her to run smooth. Almost sounds like timing issue, but I went through and rechecked everything I could think of. Engine idles and runs rough almost like running on three cylinders with the occasional backfire. I initially thought I got the timing off one tooth, but just rechecked and ruled that one out.

All timing marks line up on the crank and cam.
Internal cam gears in the head are lined up.
Coil checks out
New plug wires.
New cap and rotor.
New plug wires.
New plugs - Doesn't seem to be running rich or lean.
Completely rebuilt head with valves and springs
Webcam 294 grind.
All valves freshly shimmed.
Compression test checks about 160 across all four cylinders.
New fuel filter and injectors.
Can't find any vacuum leaks.
Checked to make sure all vacuum lines are routed correctly

I'm starting to loose my mind. Any help or ideas would be greatly appreciated.

[BondedBlowfish]

I have another throttle body and EGR that I swapped over and it didn't seem to make any noticeable difference. I have a 94 celica which I don't think has the OBDII. I'll look into the MAP and temp sensor to see what I can find. Thanks for the info!