350 TBI being a pig from 2k-3k RPM

[shortboxchevy77]

So tonight I bumped timing to 8 degrees and the truck got a lot more responsive. One thing I did notice though was that if I just left my foot in it (making it stay in drive) that at 85 plus mph and about 3500 rpm I can feel the engine start to randomly stutter and not want to gain any more rpm's.

 

[thunderstruck]

Ever got it to point of backfiring through the exhaust? This really sounds similar to a problem I had recently, turned out to be a weak ignition coil. Truck ran okay when it was dead cold, but would loose all power once it was warmed up and you put a decent load on it, like going up a hill in OD with the TC still locked up.

 

[shortboxchevy77]

I've swapped coils out with one I had laying around but that isn't saying that its any good either. That's sorta what it feels like, runs awesome cold then just turns into a pig once its warm and struggles to maintain highway speed in OD with the converter locked up.

 

[thunderstruck]

Well also, how long has it been since the tune up was done? I know I've had wires, caps and rotors fail in a short amount of time.

 

[shortboxchevy77]

There isn't 1500 miles on new everything and its all quality parts, I refuse to skimp and run junk parts. Quality wires, delco rapidfire plulgs, complete new dizzy, new map sensor and o2 sensor, the works. It throws zero codes. I'll probably toss a new coil at it today but right now I'm working on buying a 454 in a 90 suburban. If I'm going to burn this much fuel I just as well have some damn torque. There's less than 500 miles on the dizzy, map, and o2 sensor.

 

[shortboxchevy77]

Backed out on the 454, it had obvious signs of not being taken care of. I'm not sure what to do next, I'm so disgusted with the way this truck runs I'm ready to sell it so I don't have to put any more money in it.