did I jump time?

I was accelerating hard in my 93 gt while on an on-ramp to the interstate when it felt like a large boot kicked the car and It died and wouldn't restart. I can attribute the knock to all the slack in my ujoints and differential going from being pushed hard to the engine dying. I figured at 202k miles I broke my timing chain but when I got it apart I found the chain intact. The gear teeth look good on both the cam and the crank but the chain has slack. If I cinch up one side tight it's not loose enough to manually slip it over a tooth but I don't know how it would do under stress. Further, when I line up my timing marks the distributor looks to be about 24 degrees off and I can only guess that 8 to 12 is probably more correct. (I don't have an intact haynes manual any more to reference.) Is it possible with enough slack that I could have jumped time without leaving some sort of marks on the gear teeth? Mechanically everything seems to be doing what it should. As I manually turn the crank the cam turns via the timing chain, the distributor turns, and I get the hissing of air from the valves. I've got gas on the fuel rail, spark at the plugs, and I had the TFI module bench-checked for grinns. I should probably change the timing chain out since it's on the original and I have it tore down to that point. Any insight would be appreciated. For that matter, does anyone know about where I should aim for with the initial timing advance BTDC? Also, does anyone know of anything else that would mimic a timing issue? (crankshaft position sensor, etc...) This is my commuter car right now and I am stuck working on it in the evenings after work so I am trying to get the right fix with a limited amount of man hours.

the 5.0 engines start with 10* initial timing BTDC.

Thank you Cobraman. I have been busy and failed to update this. The original issue ended up being a permanent maganet in the distibutor. Got that replaced, changed the timing gears and chain for grinns, and all went well for about a week before I started getting some rough noise form the tranny. I dropped it out for a simple clutch kit change and noticed the input shaft on my tranny was wobbling and that I had no inner race left on my pilot bearing. So by the time I was done I had replaced my ujoints, clutch assy, cable, etc... and rebuilt my tranny (replacing the input shaft and associated bearings, and the thrust bearing and 15 needle bearings where the output shaft seats in the end of the input... know how hard it is to find bearings without buying the whole rebuild kit??) Any way, I got it all back together and noticed that she wasn't idling right and bogged down in any gear at low rpm's, and I knew I had not ever really solved my timing questions. A coworker gave me a heads up on the 10 BTDC and pointed out something that I would not have thought of. I had originally set my timing with the jumper plug in. I did not know you had to pull it and set your timing and then plug it back up and let the computer perform whatever compensation it will. Out of curiosity I pulled it before I did any adjustments and had the strob on and discovered that my original setting was pretty much zero. Pretty sad but I was just happy to learn something new.