The truck will not idle and is low on power. When it tries to idle it smells very rich. If driving at light throttle it coughs and stumbles. I have tried everything I know to fix it. Replaced the distributor, map, o2, tps,plugs, rotor, cap. wires. I took it to a shop that said he could fix. $300.00 later he also changed all the above items and it ran worse than when I took it in. I believe he has the timing off on it (advanced). The truck is very very sensitive to its timing, too low by a couple degrees and it will not run hardly at all, too high and it does the same and is hard to crank. I am not saying 10-15 degree swings, I am talking 2-4 degrees either way. The shop I took it to said the map sensor is losing voltage/vacuum at idle and losing control of the fuel. I did a compression check and 7 cylinders were at 120 and 1 was 150. I know the motor is not perfect but it should run. I would just like to get it through the winter until I can rebuild my 454 and put it in it come spring.