91 Trooper lacks power

My 91 Trooper 159K lacks power when accelerating and also loose speed going up hill. What could the cause of this be?

Look/listen for vacume leaks unber hood and check timing/verses RPM with an advance type timing light. Just a Guess.. G/L

Checking for Vacuum leaks is sound advice. Does the vehicle sputter, bump, or hesitate? Or is it just suddenly wimpy?
Check regular maintenance stuff -- spark plugs, rotor, air cleaner, fuel filter, et cetera...
Check for a plugged catalytic converter.
Check timing.
Check fuel system. (Plugged injectors?) Many shops can circulate a potent solvent through your fuel system and inspect the injectors for a few hundred dollars. Usually makes a big difference in performance.
Still no power? Have your cylinders compression tested. (Yikes)

Look/listen for vacume leaks unber hood and check timing/verses RPM with an advance type timing light. Just a Guess.. G/L

The timing is correct I checked it after installing new distributor cap.

I don't know how to check for vacum leaks.

Checking for Vacuum leaks is sound advice. Does the vehicle sputter, bump, or hesitate? Or is it just suddenly wimpy?
Check regular maintenance stuff -- spark plugs, rotor, air cleaner, fuel filter, et cetera...
Check for a plugged catalytic converter.
Check timing.
Check fuel system. (Plugged injectors?) Many shops can circulate a potent solvent through your fuel system and inspect the injectors for a few hundred dollars. Usually makes a big difference in performance.
Still no power? Have your cylinders compression tested. (Yikes)

I recently drove this vehicle 1,700 miles and gave it a basic tune up, new air filter (K&N), sparks and wires, distributor, oil change, fuel filter, correct tire pressure, etc.

A mechanic recommended a solvent you put in the fuel system it costs about $10 he said do it once or twice a year.

The engine isn't really a sputterer it just won't accelerate going up hill and I have to shift down to 4th and one time into 3rd.

Do I possibly need a new O2 sensor?

Do I possibly need a new O2 sensor?[/QUOTE]

From the looks of your latest post, you need a new tranny. This tranny could be the cause of your power loss. Better have the tranny checked out. Check the fluid levels in the tranny first. Maybe look for bits of metal (God forbid) in the fluid. Yikes.

Do I possibly need a new O2 sensor?

From the looks of your latest post, you need a new tranny. This tranny could be the cause of your power loss. Better have the tranny checked out. Check the fluid levels in the tranny first. Maybe look for bits of metal (God forbid) in the fluid. Yikes.[/QUOTE]

LOL. God forbid! It does need a new transmission.

Doesn't sound like a tranny to me. More like the classic symptoms of a plugged fuel filter (which you have replaced but you wouldn't be the first person to need more than one filter) or cat. Thus, I second the cat as the potential problem. In fact all of Literate Trooper's other suggestions seem right on.

I wouldn't rule out a vaccum leak however it usually has the most severe symptoms at low speeds. One way to check for a vacuum leak is with your ears, maybe helped by a mechanics stethescope. You can also spray something like carb cleaner around potential leak sources and listen for engine rpm changes when/if the new fuel is sucked in. Of course you can do this wrong (e.g. do indoors, use to much or too explosive a fuel, etc.) and your heirs can worry about the vehicle problem as you will be gone. For that matter you could listen for leaks wearing a necktie and lean over a fan belt and get similar results. The point being you need to know what you are doing and do it safely. If not take it to people who do.

If the problem started after the work it could be as a result of something you did. For example, wrong or bad plugs or wires. If you live in a real dusty area and oil the K+N filter too much that can form a sludge which can severly impede air flow. Wrong distributor timing could also cause problems.

Dragging brakes would also slow you down but I suspect you would have smelled them.

Could be an Oxygen sensor problem. However you would very likely have noticed a big dropoff in overall mileage which you are not reporting. You are also not reporting a CEL which I would think many of the possible causes would also set. Have you tried pulling them just to make sure none are set?

Bottom line, if it was me I would recheck all the recently done work, add a bottle of techron fuel system cleaner to the gas tank, check fuel pressure (or just throw a new filter at it and dry out the one just installed and keep it as a spare), check compression and if that comes up good try the Oxygen sensors.

The transmission needs some work and the clutch is out now so economy is secondary at this point.

I'm waiting on a reliable home mechanic that my Dr. friend uses for about $15-20 an hour to replace the tranny, clutch, and possibly do some engine work.

Since I'm in there might as well replace the manifold gasket too.

I'll let you know what happens.