This problem started after I changed the battery. I hadn't changed plugs in a couple of years and then did not change wires or coil boots so those have been changed. Checked the coils and they are all good. Checked the tps, it was bad. Changed the tps but the problem persists. I'm thinking it could be a bad injector but hoping its not. I haven't compression tested yet either. Both are on my list. Also, after I put in the new battery the charging system light would come on for about 30 seconds at cold start, shut off and does not come back on while running. Could a bad alternator cause hesitation? Help please!

 

If the 99 Taco got the same brown plastic injectors as the 99 4R I would suspect the injectors, what is the misfire code. I would also check the voltage output on the ALT at idle and 2000RPM's, I've seen them over charge at 18Volts and do weird things, and I guess could damage electrical components/sensors, and under charged would not help either. Other thoughts are Crank rotor and sensor, loose crank bolt, ECT temp for ECU fuel trims, CAM sensor, plugs and wires, MAF, O2, Valve clearance, bad ground wire/short and the list continues.

 

Thank you. I changed plugs, wires, coil boots and tps. Checked coils and they were good. I had the alt checked but it tested good at the time. It could be an intermittent issue though. I dont know the difference in injectors. How do I know which ones are on my engine? This was a crate engine installed at 200,000 taco now has 398,000 on it. Maf sensor is good as well. This truck also has an aftermarket security system on it that only goes off after disconnecting and then reconnecting the battery. I pulled the fuse from it. Note: after I replaced the battery it hesitated also. I cycled the ignition 8 times to reset the security system. This fixed the problem for about a week and then the problem started again, without battery disconnect. Im going to cycle ignition again and see if it fixes the problem again. If so, there is my culprit and that system will be removed. I will let you know what happens.