All of my idiot lights stay on after the engine starts (airbag turns off).

I checked the error codes. Had 13 (pressure sensor intake manifold) and 17 (O2 sensor). Cleared the memory by disconnecting the battery. Checked codes again and only 13 displays.

Any idea what is causing the idiot lights to stay lit?

Any idea how to fix this error 13. I do not know what to look for or what to replace.

I have a 90 vert with 115K miles.