What is wrong with my 93 toyota celica gt 2.2l?

[Gothicabra]

today while my wife was driving to her moms to make christmas candy when our 1993 toyota celica gt started doing some odd things. first the rpm gauge and temp. gauge dropped to zero and quit working in the middle of driving. she says it isnt shifting out of what she believes to be second gear.(automatic I wouldnt know exactly what gear.) also she is hearing a rattling noise like something broke under the hood. i would at first think we slung a rod because of low oil but it still accelerates fine so i think something could be in the tranny bouncing around. normally when you put it in park it revs up alittle high because I had to idle it up to quit it from dying at every light. the car im sure had a timing issue before this happened because there is a bolt holding down the distributor cap that is slotted and when i adjusted it all the way to one side (counterclockwise) then the car ran ok... not perfect but ok. I tried other distibutor positions but this one had the best results. the timing i believe made it hard to crank in the mornings (more specifically in the cold) and would backfire but after warming up would be ok. i told her to ask her family to check the fluids when she got there and they discovered it was almost 2 quarts low on oil. they filled her back up and the noise quietened alittle but is still apparently there. I talked to a buddy of mine and he said maybe a cable broke to the tach and/or temp. gauges. he also said that the over-drive could have malfunctioned. she drove it everywhere with the overdrive engaged so not hard to believe. also i talked to another mechanically inclined friend who said that maybe the ignition module could be bad. also believable because back in the day we had someone try to put in a stereo non professionally and shorted something out causing the lights and everything in the car to quit working (as you may know installation of a stereo involving making a connection to the ignition switch). it is a front wheel drive car so i think the rattling is either something in the tranny (cuz the engine still accelerates fine but doesnt explain why the noise volume decreased after the oil was put in) or possibly the tach or temp. gauge cable rattling (still doesnt explain oil making it quieter). well guys i gave you this much info because i really really really need some kind of diagnostic so i can proceed to fix this so what I ask is after reviewing this can you enlighten me on what is wrong with it? or maybe you know how to fix it and would like to share? this is our only car and only ride to work so it is VERY VERY important to us. well, thank you for reading and thank you for any answers in advance. have a great one.
hmmm... i would prolly lean more towards low compression because the engine revs just (based on sound) it sounds like it is revving higher than before. any thoughts?

 

[the_boy_toy]

I would think a rod is broken. If the rod broke right at the base, the engine would probably have no problem to keep working other than the loud rattling noise. The reason the transmission cannot shift out of 2nd gear is because the engine cannot rev fast enough for the transmission to shift. Low RPMs or no compression in one of the cylinders will cause the tach and temp gauge to stop working. I don't know why but I've seen it happen many times.
FYI: you are suppose to drive with the O/D engaged. The only times you turn it off is when you are pulling a trailer, climbing steep mountains or in constant stop and go traffic.