1997 Chevy Blazer Jumped Timing

One of the usual problems with chevy blazers are the intakes, depending on the one you have, the gaskets seem to fail thus allowing pressure leaks and sometimes water to get into the injection cycle.
Todays electronics and onboard computers have made it possable to run vehicles on lower grade fuel mixtures, thus allowing your engine to run without a load. While under a load, your engine fails to prospectively operate. I would have to say the first thing you should do is check cylinder pressure. Then see if you can barrow a code reader from say like advanced auto or one of the other automotive shops that have them. That will tell you if you have issues as well. Then after all that, tear the top off and replace the intake gasket and then I would think your problem solved.