I changed the upper and lower intake manifold on a 1993 Se and when it was all back together it would not start. Just curious if there is a common malady or mistake that would cause this. If not, the best way to track down the fire, air, fuel problem. It ran prior to the change.

Changed the manifolds, or just the gaskets?

If you changed the manifolds, did you change the injectors also? Did you hook them up correctly? The connectors are numbered. Left to right on the front (facing the engine is 1, 3, 5. Rear is 2, 4, 6. Double-check this. We've seen them get swapped before, and swapping a pair front and rear would take out 4 injectors, preventing starting.

Plug wires.....did you undo any of them? I'll assume your fuel rail is connected, or you'd know when it spewed fuel all over. Is the vacuum line connected to the fuel pressure regulator on the fuel rail? If not, the pressure may be too high. Did you connect the throttle position sensor, maf sensor, and Idle Air Controller on your Throttle Body?

Things to check and double-check. We all goof occasionally.

Will double check these. I photographed and made notations. Think the injectors are hooked up correctly. The wiring harness and clips were still intact and kept the leads in their appx. location. I did have trouble with the plug on the end of the wiring for injectors 2,4,6. The first went to a temp sending unit in the intake, the second went under the throttle body (yellow wire & black wire, blue boot). A friend assisted and put the final plug on (I couldn't locate it).
Thanks for starting points...a little adult supervision.

The Chief has wings again!!
Turns out (knock on wood) that the water pump/serpentine/upper and lower intake gasket change wasn't the flaw that kept it from starting...but spark plugs that were toast!!
I've raced and burnt various components...but I hadn't seen a ground electrode thinned to this degree. There was enough of it gone to cause the gap to be over .1 vs .06.
The owner (friend of mine) swears less than 12 months since they were changed and no problems. Talked to the guy who did it and he confirms. Said he changed the wires.. but these are OEM, firing order numbered, in the original looms, heat caps etc. Odds of these actually being changed previously? Like to get a quick ohm check on them.
Seems to run allright...this is a far cry from my old 455.
Thanks for help,
I'm off to track down solutions for the cars various ailments (boy, the turnsignal lever et al looks like fun!?)

Guth, if the wires are numbered, head to NAPA and get a set of Belden Premium plug wires. Ditch the OEM'*. They're good wires, but long past their lifetime. Belden Premiums run many of the fastest and quickest cars here.

I'd bet a little that those plugs said Bosch on them didn't they? Bosch acknowledges the quick breakdown of their plugs in a waste spark ignition system such as ours.

On the wires, Beldens/Autolite Professionals and AC delco are 3 of the best lifetime brands we can recommend.