power loss

I suspect an electrical fault. Could be poor ground, a computer, sensor, etc. These can be difficult to find unless they die completely.

what kind of ground would it be? where should i look? any ideas?

There are lots of ground and positive positions that can do this IF it is the problem. Normally, you would start at your battery cables and work from there. An intermittent connection can give you a ton of trouble.

Sometimes the darn cables themselves are at fault. GM makes battery cables that have two or three main cables connecting at the battery. Inside the battery terminals, sometimes those cables corrode and you lose power to one or more functions of the engine control system.

There can also be bad connections at the plug to the PCM (powertrain control module), etc. They may not always be bad, but may go bad on the rare occasion. Using dielectric grease on the terminals helps keep them functioning.

Sometimes the computer modules themselves have components which have nervous breakdowns under temperature and load. These are damn difficult to find, because they often recover before you can isolate them.

Same goes with ignition control modules, crankshaft sensors, etc.

Have someone run the codes on your OBD system and see if you are lucky enough to have set a code. If not, it may be a long row to hoe before you find the culprit. And although I feel it may be in the electrical system, there could be other things involved as well.