2002 Venture sometimes won't start

My 2002 Chevy Venture Warner Bros Addition has developed a non starting issue. It will crank but often won't start. It has a mind of its own. I can leave it & come back latter & sometimes it will start, sometimes it won't. Or I can disconnect the battery, wait 15 to 20 min, re-connect the battery & it will start right up every time. Fuel pressure is at 42 to 45lbs steady, starting & running or when it won't start with key on. It's been at the mech shop & I was told maybe ignition senser in stering column might be bad, maybe fuel filter bad, senser in key might be bad. Replaced fuel filter, no help, new keys with chip & reprogrammed, no help, mech estimate to replace stering column senser was $700 to $1,000, not doing that. I don't know if it's an anti-theft issue or a mechanical issue. Anybody have any ideas?

Well first of all, what about the THEFT or SECURITY light?

When you turn the key to the "on" position(don't crank), the light should come on for 3 seconds and then go out......if it stays on, and doesn't go out, then the vehicle is not going to start......if it goes out, it should start.....

Has the vehicle been scanned for "P" and "B" codes?

Has any aftermarket accessories been added, like a remote start?