Could be a carb diaphram issue (pinhole or slight tear) also could be dirty carb and air filter or out of adjustment . Review Previous Threads on carb cleaning and adjustment . We have gone over these items numerous times . I have indicated to Ceezaah an effective carb tuning sequence that may well assist you . Ensure you have fresh gas good spark plug and treat the fuel with a concentrated cleaner treatment . Let us know how you make out . Depending on how old you trimmer is it may require a carb kit and overhaul .

If you have an automatic transmission, you may be experiencing problems with the lock-up clutch. A sensor controls the voltage to the lock-up clutch and this is a common failure with GM lock-up clutches. The fix is simple - replace the sensor. To diagnose, temporarily disable the clutch by unpluging the lead to it. If this is the problem, it disappears when unpluged and re-appears when reconnected. The sensor is failing. Within the range of 45 to 55 mph, the lockup feature may be disengaging and engaging when the throttle position is suddently changed by a significant amount and will cause a small lurch. This is normal, however, lurching increases when the torque control part of the engine mount is worn. It may need replacing.

If it is the waterpump I'd expect that you'd either smell antifreeze or see it dripping. The light should go off as soon as the coolant level is correct. For now, ignore the light--just add coolant to the full mark, and then keep an eye on it. If it doesn't drop and the light continues to stay on, the low coolant sensor is probably bad. If it does drop, you probably have a leak--I'd suggest taking it to a service station and having them pressure-test it. (I think you can also go to Autozone and rent a pressure testing kit--it's pretty easy to use).

First, I don't live on my PC, I was away all weekend. So your not getting a run around. Second, you have NOT described the problem sufficiently for me to know whats wrong with your car. One thing is certain though, I do NOT suspect the torque convertor (a transaxle component) based on the pieces of information that you have provided. Now that is not a diagnosis that is saying it's not bad, I'll repeat, I don't suspect it's the problem. But there is a definate problem with getting you to verbalize in a way that allows me to "feel" what your car is doing without me having first hand experience driving it while it's acting up. You cannot blame a shop, a technician, or someone on this board, be they a technician or not for your failure to be able to communicate to us(me) exactly what your car is doing. FWIW, it's quite likely the problem with your car is engine control related. But before I type out a series of questions in order to attempt to draw from you what I would need to know in order to even try and figure out whats going on, you have to agree to answer them in a yes, or no fashion. Plus then add details as you feel necessary, without trying to decide in advance what you think the problem with the car is.