93 gmc bad miss under load

i got a 93 gmc 1/2 ton w/ the 5.7 and a 5 sp with od. i do have a cracked head or head gasket that makes me burn coolent. i have never had any problems like this before. i can drive in first and second just fine but when i shift to third fourth or fifth it misses bad and i noticed that it drops a little oil presure. i can keep speed just fine.its only when i try to exelerate. ive had this problem 2 times before. when i shift to 4th and hold it to 75mph it stops and runs fine for a few weeks.

Low fuel pressure, clogged fuel filter, plugs, wires, cap, leaking gasket getting water in the cylinders are all possibilities here.

i have checked plugs cap filter wires and the coil. the truck will drive this way for many miles.i put on about 400 to 500 miles a week so it would happen more often than once a month if it were moisture in the cylinders.

You cannot expect flawless performance with a bad hd gasket or head, whether or not the condition is related to that.