'89 5.0L low power issue, needs help with towing

Hi everyone!

I have a 2wd 1/2 ton '89 Sierra with 107,000 miles, in great condition overall, but the power has never been "there" for me. All we have is a 22ft travel trailer, and it barely pulls that.

A couple years ago, the stock Y pipe broke, and we built a true dual exhaust for it(no cat, 2-1/2" end to end), which helped some, but still.... this is one anemic horse. Almost seems like it's always run lean. I'm sure the dual didn't help the lean issue, but we did gain -some- power.

I have a fresh tune up(plugs, cap, rotor, etc...) and a new fuel tank and pump two years ago, too.

I;m considering changing the rear gears from the 3:07 as a first course of action. I believe 3:73 would be ideal, but figured I'd ask first if anyone thinks lower or taller would be best for this combination. Next, what ca be done to the engine itself to help it along?
As i said, it has always felt like it runs lean, but how do we "tune" these things? Can I bend the tab on the TPS to make it 'think" it is getting more throttle? Do I have to change the chip? To what, and how? Pressure regulator? Hot wire the pump for more voltage?

We don;t use this truck much at all, and it would be a shame(and expensive) to replace it just because it has trouble towing our trailer a couple times a year. Any help would be highly appreciated!

Mario

I should add
that when i said "shorter or taller gears, I refered to the 3:73 set. The stock 3:07's are way too tall already. Also, I live in ontario, Canada, and don't run on insterstate type roads, so speed isn't a issue. Max speed when towing would be around 60-65 mph.....

You could check the fuel pressure to confirm the possible lean issue, 10-13, the gears are the answer to the better pulling power, the 305 was notoriously down on power, especially for trailering.

Thanks, I'll check on the pressure deal as soon as my bud with the tools gets back from his spring trip with the kids...

As for the gears, yeah, I know tha's the big ticket for towing, but i'd still like some responses as to what the ideal gear is. I would rather not go too low if it's unnecessary.

Also still would like to hear of any simple hot-rodding tricks, if any, apply to this engine.

Nothing else?

An rv/towing cam from any number of sources, a free flowing exhaust, will allow some mid range towing power improvements. As I said because of the heads this engine is limited.