I'll start with a little background..I did a swap in my 1976 Toyota Landcruiser with a 1996 5.7L vortec. It idles smooth but under throttle it sputters almost like a misfire..it will smooth out sometimes and then start up again. I have replaced the following: Spark Plugs, wires, fuel filters, fuel pump (was and still getting good pressure), distributor and cap, and added a Mallory HY Fire off road ignition system. And none of this has helped! Any suggestions! Let me know. Thx Ray

 

crankshaft sensor

 

Thx for that I just got one and will give that a shot! Thx Again!!

 

Tried that didn't work..In low range it runs ok because the higher rpm's. In high gear it is has no power just spudders and backfired.

 

Sounds like you have gotleaking injector(s). Put a fuel pressure gauge on it. Cycle key on & off several times-Dont start engine.
Watch gauge. Should hold steady pressure. If it drops suspect injector(s). Injectors are under upper intake.

 

check your coil wire

 

I know 98 motors, the one I did acted like that until , I got the computer reflashed by GM, BUt missing at high end, sounds like a timing issue, see theres no way to tell wheter your mil is on, what r u running carb, or the complete fuelie computer, etc....

 

Yeah....sounds like timing is off. Needs to be +/- 2deg. Only way to set it is with a scanner.