Anytime when there is multiple issues, I pick one system when the problem is ongoing, check voltage and ground.
The fuses in picture is for instrument cluster, Check for voltage at the fuses when problem is ongoing. Use a test lite. As you can see, one fuse is hot all the time, the other goes hot with the key on.
Are the spark plugs wet with fuel ? are they black ( fouled ) ? You don't have the money to take it to a shop ? But do you have money to replace a bunch of parts that don't fix the problem ? I could tell you a number of thing's that could be wrong , but without testing that would be guessing . Mass air flow sensor , ignition control module , crankshaft position sensor , How's the battery voltage ? Low voltage can cause problems , You said thought starter went . slow cranking ? Battery cable's , connections etc.... Does your brother know how to use a volt meter ? Voltage drop the starter circuit . Starter Voltage Drop How to voltage drop test starter motor circuit