ok my 1990 3.0 is running like it wants me to take it to the yard but i cant let her down i love her. it has a lack uf power and it has a tendency to bogg down if you put the gas pedal about half way down. if you barely get on it and if you put all the way to the floor it is fine. i have aready changed out everything i could think of and i am at a hault right now. i dont know if it is the oversized tires. do you think that 32x15.50 super swamper tsl's are to heavy for the truck. help me please i dont want go get a chevy while i put it in the shop and let the mechanics run my bill up. any help would be appreciated.

Might want to check the Throttle Position Sensor for starters:
http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml

When you say you've changed everything you can think of I'm guessing air filter, plugs, wires, fuel filter, and regular maintenance stuff correct? How many miles on the motor? Ever had the head gasket done or a compression check?

everything you named billydkid, and on the engine it has only aprox. 86,000 miles never had any trouble before this but i am going to try the tps and the head gasket hopefully it will fix the problem. if any other suggestions please let me know so i can get my baby running running right again. oh and is there anything i can do to get a lil more power out of my pickup. like performance wise.

The HG is a major job(about $1500-2k at a shop) on the 3.0, so you will want to make sure you have taken care of all of the little things first. It sounds like a fuel air mixture problem, since it is o.k. at light and full throttle. Look for a leak in the intake after the air cleaner or around the throttle body.

A bad HG would/should be a loss of power throughout the entire power band, though a compression check should be done to verify no HG problem. A valve shim(adjustment) could help, and is about due at over 86k, but I don't think it would cause the problem you are having, a stuck valve should also be a loss of power throughout the power band.

Check the engine codes, if a sensor is going bad it may have registered a code. The FSM(factory service manual) at the top of this forum should help you out.

Do you have a 5-spd or auto tranny? What gears do you have?
The 32's will have an effect of a loss of power, how long have you had the tires? Gear size will also effect the performance, more if you went from 225's w/4.10 gears for 5spd, 4.30 for auto(stock) to the 32's, and not as much as if you went from 31's w/4.56 gears for 5spd or 4.87's for an auto(oem upgrade) to 32's.

i have a five speed tranny and stock gears the tires are real heavy and i guess i will check the compression. thanks for the sugg.