Acceleration problems

My 94 has an acceleration issue. When I push the gas pedal the engine responds very slowly. If I try to drive it, I have to floor it only to go less than a mile an hour. The transmission was rebuilt less than 500 miles ago. New timing belt and pulleys. No check engine light. Any help is greatly appreciated. I'm clueless as to what the problem might be!

 

I would start with a tune up. New fuel filter, air filter, spark plugs, plug wires, distributor cap and rotor and check the ignition timing. Inspect all of the vacuum hoses for cracks and any that may have come disconnected. Check for any stored codes.

 

I've replaced the fuel filter, plugs, cap, wires, water pump and air filter. All with less than 500 miles. Also $7000 for a transmission. I'm truly at my wits end.

 

Does it idle smoothly or rough?

 

It idles great. But when I give it gas, it is slow to respond. No matter if it's in park, drive, 4 wheel drive, 2nd, or low.

 

If its in park and doesn't rev its not the transmission.

Dumb question but you did take the plastic off the air filter if it came wrapped right?

 

The air filter is exactly as it should be. And the transmission is perfect. The motor has about 85k on it. It ran perfect B4 the timing belt replacement. Also, they cleaned my throttle body. That's actually when I developed the acceleration issue.

 

The FSM has a few items to check for “hesitant acceleration”.

I would start with the TPS, since the problem started after the throttle body was cleaned. This component can be easily tested with an ohm meter. You can probably find the test procedure on YouTube or you can PM me and I can send you a link for an online FSM and it has the test procedure.

If the TPS tests good and it is installed correctly, I would move on to test the AFM and then check fuel pressure.

 

Here is a link to test and set the TPS.

https://lcengineering.com/throttle-position-sensor-adjustment/

 

Have you happened to check the mass air flow sensor for any obstructions in the actual air flow tract or performed the troubleshooting of the sensor when no codes are present?

 

Possibly could depending on circumstances, Have seen issues of a tree leaf covering part of the MAF sensor causing similar issues.

 

I had an old 79 CJ5 with the 304 that did what you described. I found the problem by accident but it turned out it was the EGR valve.