Problems with a 84 dodge ram 50

[zrb888]

hi, i have a 1984 dodge ram 50 v-4 2.6 liter. it has misfires and i replaced the spark plugs, wires, cap, rotor. so i checked everything. i hear like a vaccum leak but i checked all the hoses and none are disconnected or has holes in it. it was getting high fuel into the clienders but i fixed that. when it starts, it stays started for about 5 mins then lowers the rpm to about 300 then it stalls. the person i got it from said the block was cracked but there was no oil in radaitor or water in the block. it over heats but if it stalls i cant fix the overheating problem or if i fix the over heating problem i would never know cause it dont heat up fast enuff. i was thinking of replacing the v-4 with a v-6 but i want to fix the v-4 up to sale it for more. any ideas on what to check or fix to stop the misfiring?????????

[neon_rt]

The Dodge D50 series is actually a Mitsubishi built imported vehicle.
The 2.6l engine is a disposable engine. They are usually worn out (even with good care) at about 80-100K miles. The rings on these are soft and wear out causing loss of compression and excessive smoking and oil consumption. Your miss may be caused by no compression in one of the cylinders.
BTW it is NOT a v-4, if you want to use a letter in the designation, you would use an "I" as in I-4.