i have a 91 dodge minivan 4 cyl stick.turns over but no start ive replaced gas tank,fuel pump,sending unit,fuel filter,plugs,wires,cap,rotor,starter,all 4 relays on drivers iner fender,and brain. started ran for 2 days and now same problem it turns over got spark but wont catch please help

did you do any diagnostics?? u should check the compression with a compression tester... its sounds like you just about eliminated everything else.....
an engine needs 4 things to start
1. air
2. fuel
3. compresion
4. spark

we can pretty much say its getting air

youve replaced most everything to get fuel.... gas tank?? y you replaced that i dont know but....

youve replaced plugs

just check again to make sure your getting these things......

if you had the right tools, you could check fuel pressure with a gauge....check compression with a gauge....and you can check spark by just taking the boot off the plug....have someone crank the engine and hold it next to a screwdriver or sumthin.....but make sure you have a plastic handled screwdriver