slow acceleration, poor fuel mileage, erratic Scanner readings

Bought truck in June. Timing chain broke in August, Rebuilt engine completely. Added torker cam and cold air intake and heavy duty timing kit. Runs exactly the same as when I first Bought it. Cranks and idles fine. When i hook up the Snap-On Scanner, I can read data with key on engine off. Whith key on engine running, the scanner data goes haywire but the engine runs smoothly except for the poor fuel mileage, slow acceleration, and in and out of overdrive at certain throttle angles. tested TPS...good, no glitches. CTS good. MAF good. Could it just possibly be the ECM/PCM?

What do your spark plugs look like? Is your motor running rich? What is your fuel mileage? What is the year of your pick-up and what motor do you have?

94 4X4 22re automatic. spark plugs look fine. tip of exhaust fairly black. get about 250 miles to a tank.

How big is your gas tank? How many miles to the gallon are you getting? Are the spark plugs a grayish tan color? Clean air filter? What was your fuel economy in July?

13.7 gallon tank. 18-20 mpg. spark plugs look like brand new. new Bomz air filter. same fuel mileage as before the rebuild. What about my erratic scanner reding issue?

High resistance in some connection(s) may cause erratic readings. Automatics generally get less miles to the gallon than manuals. If there are vacuum controls for the trans, the trans can be affected by acceleration and decceleration.

This transmission doesn't have any vaccuum controls. The way it runs and shifts would lead the average mechanic to belive it would be either the MAF, TPS, or CTS. But like I said origionally, these sensors have been checked good. Here's another kicker, as of now, "normal" shifts into overdrive occur between 40 and 45 mph. But if you turn off the overdrive, it feels like it shifts into od anyway, but around 35mph, putting the engine under a heavy load. Any clues on that?

When you say "putting the engine under a heavy load", do you mean the rpms go up?

No. RPM's go very low, as if overdrive locks in at around 35mph.