Hi Jacob .
If you have a check engine light then you have a OBD 1 system and codes can be manually gathered..
Find the DLC, which is behind the glove box and with a Voltmeter (Analogue type )
Connect to pin 12 and 1 and then switch on the ignition the needle will start to deflect ans give out codes the long deflection is your tens and the quick deflection of the needle is your units so if the needle deflects 3 long and 2 short this is a 32 code .
But with the tank issue of half full causing you this problem is due to the hose on the fuel pump
being lose ,porous,etc you will have to drop the tank and inspect for damage to the pump fittings and hoses ,tube .also seen this happen when thefuel pump is old and very tempumental to heat and will preform bad and cause you this problem .
See if you can get the codes and check on the chart of which may be your problem .
Please get back to me if you need further assistance with this issue But please get back to me with the reply button, and not the poor or bad service, this way i can get back to you or suggest another expert if needed.
Kind regards Greg