When I'm up to operating temp and I decide to get on it, in third gear no problem all the way up to and past 4000rpm but in fourth gear it stops at around 3500rpm, shift back to third and it goes past 4000 again. This only happens every once in a while and sometimes in other gears. Like on gear is fine and the next is crap, then the next is crap, then the next is fine and so on. I've played with my av tension a few times and have it set at around 3/4 tension. I just got a new O2 sensor, and I keep everything upto date matainance wise. Any suggestions?

 

It is probably your ignition. When was the last time you changed your plugs, wires, etc?

I personally have found that getting a high output coil really made a difference with my modified LG4. I use the Proform 50000 volt coil for the HEI distributor. They are not expensive ($45) and really give you a good spark.

 

new coil, new plugs, new wires all in the past year or two. I also just changed my ICM a month ago, but I've had this problem for a couple of years. I would like to get a high performance coil though, I saw one in jegs that says "Danger High Voltage" and I thought it would be pretty cool to have.

 

It might even be your module going on the fritz.

 

Sounds similar to a problem I had; starving at high rpm.

The ignition system is always a good place to start but MY problem was caused by a weak fuel pump. Sometimes it would pump, sometimes barely. I finally replaced the fuel pump (and nothing else) and never had a bog after that!

 

And even simpler than a pump could be a clogged fuel filter.