My 1988 Chevy k2500 5.7 runs rough under load trying to check engine components but not sure what everything is or where
I would start with the basics, plugs wires, cap and rotor button. Is you check engine light on or flashing? Your truck would be OBD1 so there should be an oblong plug under the dash. It will have 2 rows of connectors and 2 of them will be marked A and B. Use a jumper wire between these, A and B. Your check engine light will flash a series of codes in long and short flashs. A long one is 10 and a short one is 1. It will flash ech code 3 times and start and end with 12, so you will get 12,12,12,?,?,?,12,12,12. This may help to get you pointed in the proper direction. When you have them, let me know or type in "GM OBD1 trouble codes" into your computer. There are dozens of free sites to give you a read out. Hope this helps.